Imperial squad

The meta progression is:
* Phoenix squad to 7*/85/g8-9
* unlock Palpatine & Thrawn
* transition to Imperial command squad: Palpatine, Vader, Thrawn, Tarkin, Tie Pilot

Since you already appear to be heading that way, I would suggest following the path that far and then diverge as you wish, e.g. Imperial Troopers.

You are level 45, so unless you’re prepared to shell out some dough, death trooper and shore trooper are a ways away from being farmable. I’d go Veers, Starck, Snowtrooper, Rangetrooper, and Stormtrooper/magmatrooper

Range is only 3A Dark side. That's easily doable. Replace Shore with Storm. Problem solved.

The advantage of going with Imperial Command (Palpatine, Vader, Tarkin, Thrawn + TFP) is that you're gearing and modding 3 pilots, or 4 if you count Thrawn. Empire might not seem like a good choice in the fleet arena since Rebel fleets with Han's Falcon are the current meta, but you still need a dark side fleet with Executrix lead to farm zeta mats and ship ability mats.

Thank you very much

I have missed out on Palpatine this time around, any idea when it's coming back around?

Averages once every 3 months.

As for Troopers, if you're farming them for everywhere but arena:

Zeta Veers lead
Starck
Shore
Snow
Range

They'll destroy the Trooper special mission and can readily handle almost any team in TW/GA/TB.

The palp event will come back about ever three months.

or just check https://swgohevents.com/

apparently its coming back tomorrow...2/14/19. Good Luck. The event isn't terribly difficult.
You are going to want Kanan for your phoenix squad. His shared counter attack is huge for phoenix squad.

It's ending tomorrow. Doubt it's returning again same-day.

If you have Discord you can follow on SWGoH events -> https://discord.gg/VRcyRD