I'm sporting an XB270HU. It's a 1440p, 144hz, G-Sync IPS panel. Of all those traits I would rank them in order of importance as:
1. 144hz
2. G-Sync
3. 1440p
4. IPS
144hz makes such a difference it's not even funny. G-sync is nearly as dramatic as well. But if you could only choose one of these I'd stick with 144hz before the rest.
- Z