Are you more of a competitive gamer, such as LoL, CS:GO, Fortnite, etc (Go for higher refresh rates) 1440p 144hz.
Or are you more of a Triple-A gamer, such as Far Cry, Witcher, etc (Go for higher quality) 4k 60hz.
If you're both, I'd have to say 1440p 144hz is your best bet here. It'll last you a very long time, and you'll have the luxury of high frames and crisp quality at the same time. 4k 60hz, isn't really reliable as of now, and honestly the sacrifice in refresh rates, isn't worth the resolution boost imo.