2 and 3-part torso dilemma

I've only had experience with 3-part torsos with minifee and dollmore Judith (which is technically 4 part... but anyway) bodies so I don't have an opinion based on a ton of variety, but I feel that the function of the "diaper" joint really depends on the maker. I didn't feel like the minifee one did much while on the Judith body it's really useful. It also really depends on where the chest joint ends - I don't feel the need for an extra joint for bodies where the line runs a bit above the navel (vs bodies with a line right under the breast where the back has less options to move). If you don't like the joint around the hip area, perhaps look for 2-parts where the chest joint starts lower?

 

I think it really depends on how you interact with your dolls the most.
If you spend a lot of time photographing them, then the extra posability may be worth any aesthetic hang ups. (As cobaltconduct said though how useful it actually is depends on how it is engineered ) If you want to conceal the joint without clothing, you should be able to clone it out in photo editing software, particularly easier when the joint is not engaged in a slouch or arch. You can also get creative with your setting in the pictures to cover it up, you can probably find some good examples when covering the no-no-bits in cinematography, and use a similar idea to hide the hip joint

If they are more of your sewing/crafting or curated clothing models, certain joints tend to bite clothes and the lower torso joint is one of them in my experience Your model will be more well-behaved with a two part torso and still be able to get some nice twists that a one part can't give you.

If you like to just gaze at them on your shelf then you have to decide what's your aesthetic priority, displaying them with more diverse posing, or not seeing that joint line.
In life I'm not sure how you'd conceal the joint without some kind of clothing or accessory...... have you considered skin matching with a mesh fabric and adding some pretty detailing to distract from it (kind of like what's done on ice skating dresses)? (Not something I've tried personally as I don't mind seeing my doll's joints)

I also agree that a joint closer to the waist may work better for your needs, provided that is an area you usually cover, else its appearance may bother you as much as the hip joint

 

I had both over the years, and for some time I was a "3 part only" person if I had the choice.
From my experience though the majority of dolls I had with the "underwear" joint straight up sucked at actually using it

I either had ones where the stomach would always violently flop out of the socket, even with sueding (Dollshe Hound/Angelsdoll) OR the doll is so tightly strung that the joint cannot be used at all without excessive force because you cannot move the stomach at all (like my Doll Family-H). I only had a few where the engineering was good and the additional joint didn't cause issues. The ones where the stomach popped out namely also couldn't stand well for that reason.
The ones where it did work were a blessing (like my old LUTS SSDF, Granado 68cm), and if they all would handle like this I'd still enjoy them. But most of the time the posing was just a hassle, and it also wasn't aesthetically very pleasing to pose anyway.

Also looking at my current crew I just realized the vast majority of them has 2-part torsos! But they also all didn't have a choice, a lot of the companies I prefer seem to stick with that design.

 

I prefer 3-part torsos, despite only owning three resin BJD because most of mine are ancient. However, my preference are male action figures, and most are 3-part torsos, of course they pose better because they are hinged joints instead of elastic.

Instead of thinking of the hip joint as underwear, I think of it as looking as an actual hip bone - as an actual human skeleton. I love anatomy, as a traditional artist having done a lot of medical/anatomical drawings as a freelancer, it just makes me think of the actal hip-bones. Which I love, and don't mind one bit. I like it aesthetically as well as for added range of motion, and if I could all my dolls would have 3-part torsos because I find them more aesthetically pleasing to look at, even if the hip joint doesn't work, but in my experience based on the dolls I own they do work well enough for me. (:

 

I play with my dolls and pose them a LOT. 3 of my 5 dolls (two Dollstown bodies and a Doll Family-H body) have 3-part torsos that function quite well, and I'm constantly engaging their chest and hip joints for posing. Without those joints my dolls can't realistically lounge, lean, slouch, and embrace/hold each other close. Posing is very important to me, so I'm all for 3-part torsos!

I think the way the chest joint is cut also makes a difference. I think a 2-part torso joint cut around the waist is more useful than a cut right under the bust for mobility reasons. I happen to think it's aesthetically more attractive too: because a poorly cut torso joint can slice across the back and separate the back musculature in an unsightly way. I think an under-bust joint risks doing that more than a lower joint cut, especially if the sculptor didn't give as much thought to anatomy. A chest joint cut lower, or an actual waist joint, preserves the appearance of the upper body so that it looks good in photos from both the back and the front.

Example... the DF-H 65cm boy body has a 2-part and 3-part torso option. The 3-part torso cuts the chest joint lower than the 2-part torso and you can see the effect if you look at pics of the doll's back. Aesthetically I prefer the chest cut on the 3-part torso a lot more - and I bought that body for one of my dolls.

For me, I take many more clothed photos of my dolls than unclothed, so most of the time I don't see my doll's joints (although I still like aesthetically pleasing bodies because I know what's underneath the clothes, lol). But I'm with @Enzyme - I see BJD jointing like doll anatomy and I find it attractive - if it's designed well! So I really don't mind if torso jointing appears in my photos.

Ultimately it's finding your sweet spot between aesthetics and functionality. I like versatile posers but also like aesthetically pleasing bodies with well-designed jointing, so I'm still figuring out how to have my cake and eat it too.

 

DV's bodies originally began as 2-part torsos. I believe the 3-part torso was introduced very recently to make their bodies more modular and swappable. Eg. Achelous Lost in the Vortex and Uncia Snow Leopard both come with a 3-part torso option, so you can swap between Achelous' mermaid tail and Uncia's leopard legs while keeping the same doll on the top.

So that waist joint seems to be designed for modularity. I'm not sure whether it's also designed for posing, but DV makes well-posing dolls. You'll probably have to wait to see people's reviews, as this 3-part torso is quite recent.

FWIW, I have a human DV doll. It's very good at posing, but -- to stay on topic with this thread -- its underbust joint is the least versatile joint it has. It doesn't have as much range of movement compared to the chest joints in my other dolls. This is the only doll I own that has an underbust chest joint, but I'm already not so keen about underbust joints as other kinds of chest joints. XD

 

Most of my dolls, including all my MSDs, have 2-part torsos. I find their torso posability to be adequate for my needs. I also prefer them aesthetically to the look of 3-part torsos with hip joints. A few of my tinies have them, and while they work, they don't do too much at that scale.

My Racoon doll has an under-bust torso joint that's more sophisticated than most. It's lower in the back than the front, and has notches that allow her to lean forward to various degrees and hold her pose.

 

A 3 part torso is going to have utility if it's cut right under the chest and then another cut at the waist. If one of them is cut at the hips instead ("underwear" joint) it's not going to be that useful or naturally posing.

After all, no human actually moves using their hips. Try it! You will just be using your waist to move it. Your waist is what moves you around. The joint cut right under the chest is useful for fully curving the torso forwards and backwards.

Basically, if you want a 3 part torso that will deliver on posing that a 2 part can't do, get one where the three parts are the upper chest, the lower chest (ribcage to hips), and the lower half as one. Don't get one with an "underwear" joint.

 

I definitely prefer the three-part torso for posing reasons. Especially if my doll has good mobility thigh joints, I can use the chest joint and pelvic joint to have them sit with their knees up to their chest. However, if I had to get a two-part torso, I usually look for the ones that have more of a waist joint (about at the smallest part of the waist) than a chest joint (right at the bottom of the bust part). The waist joints seem really natural to me.

As several here had already pointed out, it's good to know if a pelvic joint actually does anything in advance. Imagine my disappointment to find out that the Fairyland one is about 98% useless, just wobbles a bit from side to side. I always find photos of what the joints are capable of these days before I buy, and some joints are prettier than others (or just easier to hide).

 

Haha, no, I've been looking into alternatives that pose better. The new Soulkid girl body, for instance, poses really well despite only having a two-part torso. And, may I add, is much more affordable.

 

@maple.honey It's not to say that you can't move your hips at all hahaha, but you move it by controlling muscles in your waist or muscles in other places like your legs, as I was taught in school when studying anatomy for animation. Putting a joint in an underwear shape there is just only going to be so useful compared to cutting the joints elsewhere

 

If I have the option to get 3-part torsos I normally go for them, unless I really like how the 2-part looks. I have found that the 3-part torsos that I own don't exactly help with mobility, it might just depend on the brand but that is my experience. I don't really mind the "underwear" look that the joint causes as I don't find it to make much of an aesthetic difference whichever I choose. I find that your doll doesn't need to have a 3-part torso to offer great mobility, it just depends on the sculpt of the body.