The resolution you need for gaming will ultimately be determined by your PC’s GPU, and how much of a budget you’re working with. Expect to pay more when you are wanting to enjoy high resolution gaming.
1080p is the most common resolution amongst gamers but, as new games and PC technology are released, expect 1440p and 4k to be the de facto standard for the everyday gamer.
One thing to bear in mind, however, is that going from 1080p to 1440p (or 4k) will have a significant impact on the performance of the PC. This will have a particularly large impact on gaming performance, reducing the number of frames your PC can drive in any one game.