If you use MB Lab or Makehuman, your best bet is to just toss the original textures and make your own (though if you were going to do that anyway, not much loss there). Human Gen appears to use much higher quality textures. MB Lab and Makehuman use 2K textures for the entire body. I've given up on MH and MBLab and learned to model humans myself because I hated the results. Trying to make the ugly presets less ugly is hard. Collar bone area in particular looks weird, and I'm not impressed with the cartoonish female body presets, ugly male head presets, and the Eevee shader is just awful.

MB Lab can look okay, but the figures are also often exaggerated and some of the presets are quite ugly and unrealistic, while many features simply don't work or break in use. There are custom morphs you can add on to make it semi-usable. MakeHuman gives rather ugly results (particularly the eyes and weirdly shaped female chest) and lacks definition in a lot of areas despite it's relatively high poly count. Daz, Fuse, and Character creator will all give you better looking, higher quality results, and HumanGen looks MUCH higher quality as well. MH has generous rights CC0 as well, MBLab not so much. They're okay if you can't model humans, but want art with human characters and don't want to pay money. You will not get results like Human Generator with MH or MBLab no matter how hard you try. I don't want this to sound like an ad, but they're very much an issue of 'you get what you pay for,' unfortunately.

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