Those going for the flagship, the RTX 3080, should get at least a 1440p 144Hz monitor. 1080p, even at 240Hz, isn’t the best use scenario for this card. The sweet spot is 1440p@144Hz or 240Hz, 1440p Ultrawide also at 144Hz, or 4K@60Hz. If you want to game in 4K and happen to play both single-player and esports titles, you can go with a 4K@144Hz monitor. The RTX 3070 should feel at home coupled with a 1440p 144Hz monitor. On the other hand, you could also get a 1080p 240Hz panel. 4K should be too much for this card but it should achieve 4K@60fps in select titles. As for the size, that’s up to you to decide.