Okay it's your choice which one you want to go with. I would recommend the 660 FTW now that you posted it, it outperforms the 750 Ti by a noticable amount.
Can I ask what CPU you have? In games like Arma and DayZ, your cpu is the prime factor in your performance, and also the stress on your psu, which is very important.
The 660 is a very large improvement over the 7770, and I myself came from a 7770 to EVGA's 750 Ti FTW model.
I don't want to sound like a fanboy now, but EVGA is a great brand, and their FTW models are truly the best for each chipset.
The 660 would probably run BF4 @ medium settings on a 1080p and high-ultra on a 720p monitor.
No you're wrong. The 660 FTW is more than capable of 1080p gaming in ultra settings. Even the 750 Ti that i mentioned earlier can handle a larger map with 64 players in ultra 1080p at over 35 frames.
I recommend the 660 that you linked. It is the FTW model from EVGA, a great brand, and will be enough for your gaming needs as long as you run a single 1080p monitor. If you want to add more monitors, different story.
If you have an FX 6300, you will be fine with this card even in large, demanding maps. I'd go for the 660 myself! Hope I helped!
Yeah like I said earlier, I would recommend the 660 that you showed us earlier. A 660 would be perfect for your setup and you should have no problem playing any game you want at ultra or near max settings in 1080p. I would go for it!