Through my testing, any arc ergo with arc conductor is the best. I personally love the light weight frame. In fact, it is so good that I would safely predict a nerf to said weapon. It needs no seasonal mod to be as strong as it is. Anything that is close quarters or have hordes of enemies makes the thing shine with just a powerful swing. Great for picking up things that need delivered. Power swing, pick up said item and arc conductor is still active. The other types feel niche and balanced. Can be good, but worth the exotic slot in things like gms? Ehhhh all depends on a play-style.

I’m partial to a Solar Caster Frame with [b]The Perfect Fifth[/b] myself; the Heavy attack lands enough hits to guarantee a Scorching detonation on its own. Pair it with Solar Subclass Fragments to amp up the Scorch damage or Prismatic to gain the bonus damage while Transcendent. Also strong with [b]Song of Flame[/b] active as it allows you to build up additional stacks of Scorch with each attack. (΄◉◞౪◟◉｀)