Once you're talking end-game sets it depends on what you want to do. Hunding's is a pretty compelling set at any level (I use it on a stamblade in vet trials). Twice-fanged snake is good for group PvE, vicious ophidian is great in vMA. Then there's the group support sets: night mother's, alkosh, sunderflame, war machine, etc. Those are more useful in trials and in that case you'll be coordinating what you're wearing with the rest of your team.