Whats the best team comp with the characters I have? Why?

Not sure what level you currently are but for now I'd probably go with Barriss Offee (L), Darth Maul, Ima-Gun Di, Asajj Ventress, and Count Dooku.

Why? Mainly because they're your highest star characters.
But in addition to that, Barriss is a strong healer and with a leader ability that gives everyone extra health. Her heal is able to ignore any healing immunity debuffs as well. Dooku has a 100% counter ability with bonus attacks. Maul and Asajj are fairly decent damage dealers.

You could also go with an all Jedi counter team consisting of: Ima-Gun Di (L), Barriss Offee, Ahsoka Tano, Kit Fisto, and Jedi Consular.
But the only downside is Kit Fisto and Consular are only 2* and would be fairly weak.

Currently, I am level 30. I've seen some post about Barriss and Dooku being a good combo. Ill try out both those setups you told me about. Thanks! Any other input would be greatly appreciated!

Level up the Jedi and run Gun Di as leader. The counters are killer. I borrowed Gun Di and 4 of 6 Jedi countered on one opponent. It was glorious.

I need to get my hands on Old-Ben, I think that Bariss, Old Ben, and Ima-Gun Di might be pretty brutal together. Maybe combo'd with Dooku and Maul for now.

I think the high crit based scoundrel teams once people start unlocking the right combinations are going to be jedi killers. I dont even have Lando fully geared yet and he is critting over 2k on his main attack and with Sid leadership he crits a lot. With Boba as tank and Cod as second dps who is designed like Lando to excel with other scoundrels in team and two healers, it could be viable end game.

I now have a 4* Mace Windu and my Jedi Consular is now 4*. I am looking at 4* Ima-Gun Di (L), 4* Mace Windu, 4* Bariss and 4* Consular and 3* Dooku for my 5th. I also have 3* Ahsoka, 4* Darth Maul and 4* Asajj to work with. Ran a few missions and my characters do counter a ton with Ima-Gun's Leader Ability.

I'm going to be brutally honest...As a Level 85 player with 14- 7 star characters, I can't find an end game team comp from those characters. Not a viable one anyways. There is potential for a good Jedi team because of Ima Gun DI, Barris, and Ashoka, but you would need some combo of Anakin, Qui Gon, Yoda, ETC... My advice is this, find one full team such as Empire, Rebel, Sith, Jedi, and farm them to 7 stars gear 11. Once you have one good team you will do better in arena, be able to get more crystals, spend them on energy, and use that to farm other characters. Just my opinion! Hope it helps!