I've mentioned complete mesh avatars several times in this blog. Heck, even Linden Lab's new "starter" avatars are full mesh bodies, which leads to frustration for newcomers when they find that the normal avatar editing tools don't work.
But, not being into these mesh body replacements myself, I haven't done any detailed reviews of them here. But Pussycat Catnap has! If you want to read up on the various products on offer, and a comparison of their strengths and faults, check this out: