I don't buy metal or plastic miniatures lately, more because of monetary constraints than preference, though. I've only bought plastic minis once - the WotC ones (a set of GoL and one of Abberations, I think). I probably have two or three hundred metal miniatures, ranging in size from a toad familiar to great wyrm black dragon.
That said, I was at my FLGS today and was looking at the metal minis, and cost wasn't the only thing that kept me from getting some really cool Reaper minis. All my paints are dry now, and I didn't have enough to begin with, and frankly, I just don't feel like painting them. I don't have the time to design adventures, much less paint minis. The paint job on the WotC minis is as good as a most of my paint jobs and a lot less hassle. They're cheaper, too, despite the randomization.
I'm not against metal minis per se, but I think I'll buy mostly random plastic minis from now on.