Note: I am only linking to skins that don't use nudity in the previews, save the rest for private messages.My tastes skew pretty "Maxis-Match", and while I know of some great realistic skins endorsed by many, they're not things I've tried myself. So I'm sticking to what I know.
Not a skin but: missy harries' Overlay Fix, for some reason EA included a pink lip overlay for all sims and it doesn't look good on anyone but especially on
darker sims. It also messes up with lipstick opacity.
My current defaults: neuroticrobotic's Spiced Cider, with previews
here. It's nice and simple, and I stuck with it because of that and how it removes some of the pink undertones that other skins (including EA's) have.
Other ones I've used and can recommend:Trees by Simarex, ignore the red noses/blush in her previews, it's not part of the skin. I have a picture of one of my own sims using it under the spoiler tag:
My favorite part about the skin is that it has a monolid version so you can more easily make Asian sims (or other people with monolids, no one has a monopoly on it), and it's the only skin I recommend that offers it.
Joedy_76's Skintone Version 4, more previews
here. It's a little shinier than the other two if you're into that look. Lovely all-purpose skin but I haven't used it in a while so hopefully that's not a corrupted memory.