This past summer, I painted up a few figs to give to a friend. All but one were Reaper figs, and they were all plastic. Really easy to paint (although still challenging to make look good). The last one was of Nuada of the silver arm, by Jim Fitzpatrick. I forget which company makes it. It was metal, and was much more difficult to paint.
It seems like the more that I paint plastic figs, the less I want to paint metal ones. At least for me, the paint is much more easily applied to the plastic ones than to the metal ones.
Please excuse the unpainted hordes in the background!