Out of those three buy the LG 24GM77, great monitor, only issue is that if you turn it off then windows will not recognise that it is connected to the GPU until it is switched back on. It's almost as if pressing the button on the front =/= unplugging the power. Performance wise, it's level with the BenQ XL2411Z/20Z/30T. You'll only get more from a screen with G-Sync / Free-Sync.
well, these screens on first list cost ~350€ which is almost same amount of money i'm gonna spend on a new pc :D aka won't have that amount of money anytime soon :D