I had bought a bulldozer-based system because bulldozer was supposed to be actually a run for having a lot of performance. The thing sucked. The "8-core" CPU is pretty much a hyper-threaded quad-core but slightly worse. It is really not worth buying. Bulldozer is legitimately a disaster and the only things AMD has going for them are 1. server CPUs (Heavily threaded applications such as databases thrive on high-core opteron systems, like 32-core or 48-core) 2. graphics cards (The ATI cards are similar in performance to the NVIDIA cards in that the highest-end AMD card MIGHT be better than the highest-end NVIDIA though that could just be false). Desktop CPUs is not their thing and I heavily regret ever purchasing one.
When the sandy bridge e came out I saw an opportunity and bought the 3930k (not paying an extra arm or leg for slightly better performance). It is better in every aspect. The bulldozer I had basically could not handle anything I run (IntelliJ being chief among those applications) and it just was not pretty at all, let alone play any games. The i7 can handle several vms, 3-4 intellij windows, and still not show any signs of slowing down. It's significantly better and IMO more worth the money. A couple hundred dollars more (Or maybe even less than that) for well over twice the power is worth it in a heartbeat.