Upgrading my oc

Hello all, I’ve currently got a pc with a 2070 in it, 16gb ram, I7 9700k etc

I just bought a 49 inch monitor and see the games are really struggling, I figured if I’m going to upgrade my full pc I might aswell go big.

I’m not really knowledgeable but I know enough, looking to ask what gpu you guys would recommend for 5120x1440 (pure performance) I don’t really want to spend above 900 (£) and I don’t mind going AMD

If anyone can offer some help and advice on when to buy gpus, that would be fantastic, thanks guys.

Title misspelled (PC*) sorry