Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
I've been using Quaquaval in OU and it's a good Pokemon. I haven't used Palafin at all so I can't say how much better Palafin is than Quaquaval. The set I use is:
Quaquaval (M) @ Assault Vest
Ability: Moxie
Tera Type: Water
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Aqua Step
-...