Faces and body types decided size for me. The first dolls I fell for when I discovered the hobby were all SD-sized, so that's what I first bought. It turned out to be the ideal size for me - That 58-62cm range is really the 'sweet spot' for me. I've dabbled in other sizes but I'm not a fan of chubby childish faces, bodies, or hands, so it generally doesn't work out long-term for standard types of mini/tiny, and event mature examples are hit and miss. The mini I've liked best is basically a 40cm SD, but he's impossible to work with because of his incredibly weird size that means absolutely nothing fits him out of the box, the second most successful mini his face works, and his body isn't too horrible, but his chubby baby hands hurt my soul. FIDs miiight work but the eye selection at that size doesn't work with my preferences for eyes. XD; Tinies don't work either unless they're mature tinies. I've had a lack of offense at Dollfie/Dollfie Plus, which are easier to deal with because barbie clothing mostly works. I've got a 1/12 scale doll who's also a mature adult and she works out well as a doll for my SDs rofl.