Right now 240Hz is a PC-only refresh rate standard, as current gen consoles can’t do faster than 120Hz. We recommend 240Hz in 1080p and 1440p, and for both DisplayPort 1.4 is more than enough. That connection comes standard on all good gaming monitors now.
We recommend those resolutions because getting games to run in 240Hz in them isn’t that hard with modern graphics cards. In 1080p, even mid-range cards like an RTX 3060 can easily get it done, while an RTX 3070 can do the same for 240Hz in 1440p. This applies to major competitive titles like Fortnite, Apex Legends, Rocket League, PUBG, Overwatch 2 and many others. None of these games are especially demanding in terms of graphics. And with upcoming RTX 40 series cards from NVIDIA and RDNA 3 GPUs from AMD, even more powerful hardware will make 240Hz increasingly popular. In that sense, getting a 240Hz monitor now is futureproofing your setup.
We can’t recommend going with 240Hz 4K monitors, even if you could find one. At the moment of writing this, no graphics card on the planet could possibly provide you with a consistent gaming experience in 4K at that refresh rate, it’s simply not doable.