First off cores and clock speeds don't really mean much anymore, it is all about the micro architecture and IPC. Intel's CPU's have a faster more efficient architecture meaning it can do more instructionsper clock cycle. What this mean is that a 3.4 GHz I5 will outperform the higer clocked AMD 4.0 CPU.
Next the Bulldozer was/is absolute crap. In gaming the I5 and I7 easily beat it even the measly dual core I3 beat the "flagship" Bulldozer. It couldn't even beat out the Phenom II that it was suppose to be replacing. Also lets not forget that Bulldozer can and will bottleneck high-end video cards. If you want to go with AMD ateast go with Piledriver but I would go with the I5 as ASH said.