Yes, almost all of these need reworks.
Mace's kit is incredibly unimpressive for a character of his caliber. Damage is average at best. The expose chance needs to be changed from a random to the enemy he's attacking. His ship is fine, you just have to use it right.
Chewie should be from the original trilogy, as we only see him for, what, 3 total minutes of screen time in RotS? Not to mention he has no relevance to the prequels anyway. He needs a new auto-taunt as well. Synergy with an improved Han Solo would round him off.
Han, unfortunately, yet another Star Wars legend left in the dust. Deadeye should do more damage and include a longer lasting stun in addition to the turn meter gain. For that, increase his crit chance. Add synergy with Chewie and Han will be the legend he's meant to be.
Grievous is also unimpressive for a legendary character. Overall, he's too weak. First things first, increase all his stats by a great amount. Improve his leader ability to include benefits for Separatists and Droids. His unique should be changed so that you chose the ally to taunt.
Old Ben should definitely get a taunt.
Savage is fine, no need for a rework. He's incredibly deadly if used in the right ways. If you save him until last or one of the last to take out, he becomes more vulnerable. He's slower, take advantage of that.
Plo Koon is one of those lesser know, saw-you-a-few-times-in-the-films characters. Not well known if you didn't see Clone Wars. In all honesty, he needs a higher chance to dispell all buffs. Force Judgement needs more damage and higher chance to inflict Offense Down. Take Charge needs more turn meter gain. His leader ability is ok, but you can't use him against Maul, as he'll just tear Plo apart. It needs to be Defense and Tenacity related or have these added, as these are huge Jedi attributes.
Bane needs an overhaul. Low quality character. Increase second attack chance, increase turn meter removal, increase stats in his leader ability, add a new attack or ability.
Factions, oh boy here we go...
Jedi are overwhelmed by competitive teams. Only Qui-Gon and General Kenobi make the Jedi capable of any kind of significant arena rank. So just to sum that up, that's a zeta ability and the hardest heroic raid reward. Not exactly helpful for most under level 80. Ima Gun Di and Luminara are ok Jedi leaders, but can't make it well in arena, much less harder Light Side Battles. One of the largest factions having some of the worst capability and teamwork, which were things they were known for in the films.
Bounty Hunters need some way to inflict more damage and debuffs, as these guys are supposed to be tracking you down and taking you out. With that said, more damage, more debuffs, high crit chance, high crit damage.
Nightsisters and Separatists both badly need some actual synergy in general. They need some kind of decent leader abilities at the very least.