Best competitive settings for AW2518H?

[Gidrah]

I have the AW2518H 240hz monitor and I've noticed my performance in games (specifically league of legends) isint as good as when I had my old BenQ 144hz monitor.

I cant push more than 144 fps consistently in most of the games I play. (League of Legends, Dota 2, CoD Modern Warfare) So I am wondering if the 240hz is more of a hindrance than helpful.

Ideas I've thought of to resolve this:
1. Lowering my refresh rate to 144hz and capping fps to 144, no v-sync/g-sync. (I'm worried about this overdrive issue I've read about and input lag)
2. Using 240hz and capping fps to 238 using g-sync. (G-sync has been wonky and adds flicker in my experience)
3. Using 240hz and capping fps to 120, no v-sync, g-sync.
(Maybe this would be most stable since 120 x 2 = 240?)
4. Using ULMB mode at 144hz (Unoptimistic about this option)

I'd really hate to downgrade to a 144hz monitor since this ones futureproof so what's the best option for low input lag with stable framerate for aiming?