But are you primary a gamer?
But imo the priority is first, high refresh rate (120hz or above)
Then size. And when you are used to 29", i think it would be bad to go down in size = 27" would be the way to go. I personally wanted G-sync, as i removes a lot of problems. But it's way out of your budget.
I just went from 24" to 27" and form 1080p to 1440p
WHAT a difference
The jump from 92ppi to 109ppi might not sound lige much, but it looks way better.
But the 300£ is a "problem. Maybe stay with the 480, and a freesync monitor?
27" 1440p and Gsync is 600£