I like these a lot. I have a few nitpicks, but really, they're minor; they're probably even negligible, but crits is crits, yes?
The first thing that struck me was the characters' eyes. They all seem to have this dead-glazed-stare-thing going on, so I shifted the pupil on our right a little to the left. Maybe I'm misinterpreting it, and they're supposed to be staring in a different direction, but as it's a sidescroller, I just instantly assume they should be looking either fully left or right.
Some of your colours are quite close together. In the case of the edited sprite, it's (mainly) the green and brown. You may have used separate colours to get that nice mixed-palette effect that these have going on in general, but personally I think the sprite looks just as good with one colour or the other.
Aside from that, there were just some minor banding issues, particularly in the hair and... armor-skirt-groin cover thing, though these can be fixed pretty quickly.
Here's the edit, if you're interested:
These really are sexy.