I asked a similar question yesterday and wasn't satisfied with the answers I got - too many just say get an i5. According to Steam Hardware reports, 49% of all users have dual core CPUs and 45% have quad core. Two years ago actually had LESS dualcores by a small percent (like 1.5%). I realize Steam isn't the only source of games, but gives a good idea. I don't see devs suddenly ignoring the larger piece of the pie by locking people out of games by requiring four physical cores. Given 6100 & 6500 are both Skylake, I reckon the i3 does a little better in single and two threaded tasks. I was ready to lay down the extra money for the 6500, but I think I've changed my mind to the i3.
(Note: It doesn't say if steams 2 CPU list is two physical cores or two threads. Maybe someone else can let us know since that could really change things if the 49% is limited to two threads)