Sith is my specialty and I've run these variations well in arena for months:
My preferred setup is: ZZDN, Zavage, Dooku, SA, ST ...
I ran EP for a long time before I zeta'd Savage. He's fine, but his AOE is useless vs fast tenacity up teams (read: Chirrut, Rex). He's also squishy, so if you're in a shard full of Rex Chaze teams, EP isn't a good option IMO.
Zaul is only good as a lead IMO, and only in specific scenarios with all the Rex and R2 teams running around.
Zavage is dependable, takes a beating and has a lot of utility.
But note, if you don't have a Zeta on Savage, I wouldn't recommend using him until you get the zeta done. If you're going to run EP make sure he's uber fast so he can get ahead of the tenacity up, at least at the onset.
Note: After I got Thrawn I ran ZZDN, Zavage, ZThrawn, SA, ST. That team did rather well. But right now I'm running ZZDN, ZThrawn, ZR2, Chaze until I get my GK in order soon. I took Dooku out as soon as I got Thrawn ready.