I was chatting with a friend of mine who is into miniature painting. he does it as a hobby mostly and not for gaming or anything like that but he is in agony sometimes about having to paint them (he isn't good at it). We started a debate about just buying them per-painted and he said that was no fun, but at the same time he doesn't have fun painting them either. Just putting this out here as to which you prefer for your miniature collection.
Pre-painted are usually way better than what I could do so I go for those but they also tend to be more expensive so that's a total drawback. But the natural silver color is fine for me too.