I'm a metal fan all the way 8)
The plastics have come a long way as they have got more experience, however if one compares the better scale model kits and the detail manufacturers like Tamiya can do, GW arn't anywhere near this decade in the quality of their plastics for vehicles or infantry...
don't get me wrong, I've always (apart from the odd appalling design concept) liked GW stuff from the time I bought RTB01 marines a month or two after they were released. 8)