Fine tuning which processor is best when the contenders are comparable is a bit pointless. Not all processes use multi-core processors effectively, so you might find a fast dual core better than a slow quad core sometimes and vice versa other times. You have to ask yourself what process is most important to you. If it is rendering within PE then the quad core would probably be the way to go. Tom's Hardware has (had?) benchmarks for different processors with different applications which show that there is no simple ranking of the different processors.
I chose a dual core with a faster clock than that of the affordable quad cores when I upgraded some time ago because I wanted best speed for general applications which hadn't been optimised for multiple cores. Rendering was important but not critical because I could choose when to do it and do something else (e.g. sleep) while it was happening.