The zeta on EP's leader ability is definately worth it. It transforms your empire team completely. With his lead zetaed and either a fast Thrawn or fast Vader, you can get the turnmeter teain going.
I see, you have worked a bit on both farmboy, Old Ben, ST Han and Leia. You may as well take those 4 all the way to 7* to unlock commander Luke. CLS will form a powerfull trio along with Chewie and Han Solo.
If you take Bossk and Jango to 7* you'll have a team ready to take Chewie to 7* as well. Gearing them up will help you in both squad and fleet arena. You're doing great i fleet arena btw :-). If you consider adding another zeta to your BH I would recommend Bossk's second zeta since it will buff your HT considerably. HT is part of so many different fleet types. You will benefit still after switching to a rebel fleet built around Han's Falcon. For that fleet you will need to gear up Biggs, Han and Chewie as well as their ships (Han's zeta is another great zeta). Also unlock Cassian's U-wing. You won't regret it. It will help you stay in top ranks of fleet arena.
I would recommend to focus on those for a start and only work on sith as side projects (Nihilus and Sion to complete your Traya trio).
