Personally I like the new M3’s better than the old ones. Actually in the market for a used M4, which I found online for around $55k-$60k with another 25k-35k left on the warranty. I do like the Porsche’s too but I would want a turbo which would come in at another 35k. In terms of bang for buck though, I think it’s hard to beat the Nissan GTR. The only thing about those is the launch control which I heard takes a beating on the tranny. I would be worried about buying used because of that.