The hat looks much better now!
Maybe make the shadow under the fighter's helmet rim a bit darker. He could also wear calf boots instead of leather shoes. You could experiment with putting a small spike or peak onto the helmet, too.
The wizard's robe might be too busy now with two different designs in varying size. I'd test it with only one or the other, both could look good I think (alternate "skin" choice for the character sprite
The upper (or rather, far awar) portion of the bases has a strange curve, especially then looking at the one the dwarf is standing on. Three pixels diagonal, then three horizontal... hm. On the whole, I like them as far as diameter and thickness is concerned. Maybe they could be slightly wider still, to accomodate future characters that have more acrobatic poses
The fighter's sword has this single offset right at the middle, at this pixel scale it looks strange, I think a 2:1 (two up, one right) would be better and still have a different angle than the dwarf's axe.
All in all, these already look great, especialkly the colors and lighting. These beg for some basic animations, just two or three frames for some elements like the wizard's flame spell, the fighter's sword and shield, and the dwarf's axe and right arm (and/or head).