The 960 is a hex core with two cores disabled but other than that the architecture is the same as 955 , but might have some more OC headroom
The FX 4100 has strengths and weaknesses http://www.legitreviews.com/article/1766/
OC to 4.6 GHz on the stock cooler .
Since all three choices are good value the choice of processor is not as important as choice of motherboard . To upgrade in future you need an AM3+ mb with a 970 or 990 series chipset