I would love an opinion from those who are currently playing this season. I got the two rings that give the set bonus when you wear ancients and no other set items and firebirds only (i have some other set pieces but not full sets yet) I have 6 Ancient pieces (not great rolls but ok) including both ancient weapon and source. Is it worth it to run the ancient set? or should I stick to firebirds until I have more Ancient pieces or at least pieces that work together instead of being random?
For Firebirds, LoN will beat Firebirds at 6 ancient pieces pretty much, unless you are used to a playstyle where you get a shit ton of burned mobs following you for huge damage boost. So yea, 6 ancient pieces, use LoN over firebirds.
It does not beat Delseres though at any level. As for Tel'Rasha, it entirely depends on the build you are doing.
Generally, Arcane Orb, Energy Twister, Explosive Blast, and Wave of Force (Which nobody uses over the other 3) builds use Delseres. Archon builds use Vyrs (You need the set bonus for Archon to really work). Everything else can be divided into either LoN or Tel'Rasha.