SUPPORT.

Clothing, textures, characters. Yes, it's possible to convert a lot of stuff from other figures, but it's extra work and often doesn't work perfectly. It's why I haven't used Dawn much. There just wasn't a lot of stuff for her. The characters available, at least in the beginning, weren't that great and all looked alike. There's more choices now, but with Dawn 2 about to debut, I'm reluctant to invest more in Dawn 1. (Dawn 2 looks fantastic, BTW.) I'm not using LF and LH much, for the same reason.

For most of the things I use Poser for, V4 and M4 are "good enough." Especially the weight mapped versions. So having that huge backlog of clothes, textures, characters, morphs, etc. usually outweighs any advantages of a new figure. I still buy them, because I want to support Poser and its content creators, but I find myself still using M4 and V4.

The other thing I want is morphability. Particularly in the face. I like to be able to make the figure look like anyone. Neither Dawn nor LF have enough face morphs, IMO. Some people can use magnets, or Z-Brush, to make any morphs they want, but a lot of us are dial-spinners. It's the reason we're using Poser, and not Blender or something.