1440 at high hz is the obvious answer. The picture quality between 4k and 1440p is so negligible even at the close distance we are at as PC users. I still advocate for ultrawide, but it does add extra stress that gets closer to 4k stress. Still, with Destiny 2 as an example, I get 80ish fps at max on 3440x1440p. However I am running an overclocked1080ti, so you need to take hardware into account.