Bulldozer & Piledriver Processors still remain the best
Overclocking solution on a budget, except maybe I would exclude the 4 core and 8 core versions because of the price. What I want to talk about is the much overlooked 6 core version, only slightly more expensive as compared to the 4 core and quite a bit cheaper than 8 cores, with less power usage and heat.
Although they do eat a lot of power overclocked its still the absolute best performance on a budget for people who really know how to overclock systems for 24/7 stability.
Intel still remains the best all round but you have to spend quite a bit extra. While you can get a 6 core Bulldozer/Piledriver cheaply(look out for AMD's more cores more cash back promo which runs every now and then!) add a cheapish mainboard with the features you need and a cheap cooling solution. Your looking at maybe £150-£170 for a new system that can run at a high frequency and have some extra cores for multi-threaded applications.
With Intel on the other hand on a budget your options for roughly the same cash is a 2 core i3 and no overclock.
Many people at this point will just go that extra £100 higher and get a i5 k series but some times it's just not worth it. My main system is a i5 k series but when I build a second system I chose the FX-6100 simply because I LOVE overclocking and the idea of a vanilla 2 core i3 seemed so mundane I just could not bare the thought

Adding yet another i5 k series just was not in the budget nor would it be utilized fully. (This is the spot where AMD has a niche)
I'm glad AMD increased performance in Piledriver but I do think they need to do a bit more with the next iteration. They need to look at increasing single threaded performance and they need to bring down power usage. Easier said than done, I learned a bit about processors inner workings this year and can imagine those AMD engineers having sleepless nights!