First off my GPU/CPU
CPU: Intel i3-2120 (dual core @ 3.3 Ghz)
GPU: AMD Radeon HD 7750
Other parts are good, these are the two still in question.
(Side note: I play at 720p and will for the foreseeable future.)
The games I currently play without a problem:
-Mass Effect 3
-Metro 2033, etc.
Games that play with some trouble:
-BF4 BETA (I know it is a beta but that isn't why it plays rough.)
-Skyrim (Shadows and cities)
- Any other game that is CPU heavy
To start with, the problem I have is that while BF4 and Skyrim are definitely playable for me there are times where surprisingly my CPU is a bottleneck. I can only play Skyrim with shadows on low or medium otherwise I get extreme latency and terrible fps (25-35 fps on Ultra). BF4 Beta is always around 85-100% CPU usage even when in a game by myself and sometimes causes the game to freeze briefly making it hard to play especially when there are a lot of players around me (like 30+) I can play with medium-high settings with fps is that is usually 35-45 which is playable for me until I start hitting 100% CPU usage.
My CPU is holding me back more than my GPU and I know that most people would say upgrade your GPU but since the games I play most/will play most is limited by the CPU more than the GPU is there any reason why I should upgrade my GPU instead (think 7870 or GTX 760) or should I go ahead and upgrade my CPU (either i7-2600 or i5-2500)
Also, I can only upgrade one since I am limited to $300 or less.
Upgrade CPU! for sure! if you can pick an i7 up for cheap (second handed maybe) then go for that one.
Everything will go way smoother, why get a new engine if you have no chasis to hold it in (this case GPU = engine, CPU = chasis).
Then if your still not satisfied, the CPU will open doors for the new AMD GPU release, they will come out in a week or so.
The options you have specified are fine too, but they will drop in price once the new GPU war will start.
And dont go for the 7870, instead the comparison is 7950/760.