what is your budget? i feel the a10-5800k at $100 offers the best price to performance ratio out of the 6800k/7850k or 860k. you can get the 860k for $85, it is slightly faster, but it does not have the igpu, so you would have to always use your 270x to output signal to a monitor. this might not seem like a big deal since you have your 270x. but i feel having the the igpu of the apus is nice if you want a second monitor, or if the video card dies you can still have a working computer than can output to a monitor for basic computer work, or down the road you decide to sell the computer but want to sell the graphics card separate and still have a fully functional computer without a discrete video card.
for the $15 difference i think its worth it. you may want to retire the current rig in a few years to home theater pc use and the 5800k is perfect for light gaming/htpc use. actually as far as games go the igpu in the 5800k is higher performing than a ps3/360(720p medium settings), so for the extra $15 for the added igpu 750k/760k/860k, i think its more than worth it.
either way you will want at least the should put an aftermarket cpu cooler on one of these processors and give it a safe but modest overclock for some free extra horsepower.