I can't put the crossfire in the 2500k because i can't afford it, also it would run at x8/x8 rather than x16/x16 and i know with blender the 6100 is better than the 2500k so tbh I need to know if while gaming the 6100 will bottleneck the graphics by alot
Go with the 2500k. It can be overclocked another 500Mhz easily. Get another 6770 in a month or whenever you can afford it. Adding another GPU is cheap compared to a whole system upgrade. HD5770/6770s are pretty cheap.
You didn't read the question it was 2 systems 1 2500k 1 6100, it's not just the chips
The systems both have identical memory and aftermarket cooling. The only real difference is one HD5770 or 2. The question is would you rather have the much faster, more futureproof system that you could add a second HD5770 to when you can afford it, or have dual graphics cards now.