Depends what PC you have, if your graphic card can run your games 4k60fps then go for it.But i prefer high refresh rate than 4k display.I'm in the market for a new monitor and this Dell 27" looks like a great price for potentially a great monitor.
Will I regret not buying a 4K monitor though? As I only use my PC for gaming I guess 144hz refresh for 1440p/gsync is much better?