Nest or General Kenobi

A 3* nest is more than a handful believe me. Just stack up the protection on her along with gear.

She once soloed 3 teams of mine in GW at G11.

Now I have Thrawn however I can fracture and annihilate her I would think.

Yeah, 3* nest is good though. Not sure I'd replace GK with her though.

I use them both.
My arena team is ZZ JTR, ZZ R2, Z BB-8, GK (all are g12) and 5 stars g11 Z Nest (11 € pack plus lots of crystals, yes...).
I'm stable at rank 24-45.
Not so great? ... Maybe, but my shard (dec 2015) is a nightmare with more than 20 Traya and 3 super Bastila teams...

If you're facing a lot of EP leads, consider Holdo rather than Nest. She also has the AOE daze but adds Resistance synergy. I put RT in rather than Thrawn in the fifth spot, and he just goes over and over with all the exposes. Destroys those super Bastila teams too.

Traya, on the other hand...

I ran the same team for months in arena, and I would choose GK any day of the week. No contest.

He takes a while for the EP teams to wittle down, and if you keep the rest of the team stealthed with R2, you'll be able to take down EP and Sion while controlling Nihilus and Thrawn. Ignore Vader. He won't do much if you have the other four guys under control.

Enfys sells herself extremely well with a seemingly awesome kit and on paper near immortality, but she falls short when the battle is on.

Enfys is way too easy to take down. The trick is to not panic. Take you time with her and allow her to take turns (let her attack or use stun, and for the love of God do not remove TM from her). Try to plan it so you only hit her with your best attacks for effectiveness.

Personally I go for JTR teams with Enfys more than enything else.

PS: I have no experience with performance against Traya on offence. I avoid that crazy old hag like the plague.

I'd love to avoid Traya but sometimes near the top it's a Traya wall and there's no way to avoid her other than not battling.

Use RT on offense then leave GK + nest on defense.

Nest is super easy to deal with though.