Need gaming setup advice.

So, I recently had a B-day and what better way to celebrate it than by moving to 144Hz 1080p,right?
I'm looking for decent GPU that can handle 144@1080p and a decent monitor.
Monitor:
Right now i can't decide between 24 and 27 inch monitors, while i would love a slightly bigger size, i'm not sure if 1080p rez will look as sharp as it does on 24 inch monitor!?
Also, I prefer really colourfull monitors and I'm wondering if TN type monitor will be okay for me?
GPU:
I currently have R9 280 3gb windforce and i need an upgrade.I'm NOT looking for NVIDIA GPU!
I'm well aware of RX 480, but i'm not sure if i wanna jump on that hype train yet. So if you know other alternative, that'd be great.

PS. I know i'm being somewhat very specific, but im willing to sacrifice some things over the others.I also should note that i am on a budget, so i don't need or want really HIGH-END stuff. Just a decent 144Hz @1080p.