For what do you want build it? Gaming? Which games? Working with photo editing? I upgraded from 1080p/60hz to 1440p/165hz with gsync and I don't see big difference. But thats only me, some other guys swear on it how different it is. That said, it can be a disappointment to you too. What is your budget?
For a general recommendation, I would say get
a) 144hz or higher with g-sync/freesync monitor and low input latency, if you plan to play fast games like Overwatch
b) 1440p if you just play single player games like Batman and want more space on screen for web browsing or photo editing