I'm a fan of 4k, but I don't really play any titles that rely on twitch reflexes and flick-shotting. If you're a competitive player of games, I'd opt for the higher refresh rate. If you play a lot of solo-play games, or multiplayer in a non-competitive manner, I'd opt for 1440p
If graphics really is everything, I'd go 4k. I did, and I'm happy with it