A lot of factors here. PPI in particular. If you were to sit right up on a 60 inch 4k TV as a monitor it would look aweful but definitely better than a 1440 monitor. From the other side of a room you probably wouldn't notice any difference at all.
Refresh rates above 120 are a scam because there isn't really anything that exists in the mainstream that can supply that kind of a signal. Someone is probably going to argue this, and that someone is wrong.
More pixels means more resources. A 4k monitor is equivalent to 2.25 1440 monitors, and you would probably be better served by 2 1440s with the thinnest bezels you can find, or else a 32:9 monitor.