Depends on what you are doing. Relequen in Overland is useless, minor slayer is wasted. I'd go with Deadly and Pillar.
But you should probably consider other alternatives like Tzogvin or Order's Wrath.

For Dungeons and Trials Relequen is best for single target, but multiple enemies? Nah...

I guess I'd get all and switch in and out depending on what I do.