Regarding the specific toons you listed: Vader is gonna be tough to boost, good tho he may be. Dooku, Daka, and/or a RG combination are extremely helpful w/ stuns. Daka is tougher since you're gathering most shards from Cantina battles. Same for Ahsoka. Once Daka is boosted some (as she starts kinda weak) i am personally a big fan, tho her heal will only ever be a moderate one. Teebo is nice with his stealth and TM control, but not a priority.
Regarding other toons in general, if u enjoy running droids, u should consider going after Poggle and Geonosian Soldier, as Poggle boosts offense and Soldier hits hard and has an assist, and they have synergies. Also, Rey. Get her. Period. And Phasma is great, and "easy" to boost in GW store.
