Cannon Busters is full of wacky people - humans, robots, and various types of animal-human hybrids - which can make quite a few great characters. While there aren't a lot of people in this show that are particularly great... people, they make up for it by being interesting and providing an outlet for you to say "ok, at least you aren't that bad."
This is a list that will go through the top 10 "best" characters, which means either the ones that are most interesting, most complex, or both. This isn't to say that all of them are bad, though - just a bit flawed. But you like your characters like that. Also, be prepared for spoilers for the series in this list. If you haven't watched it yet, Cannon Busters is available to stream on Netflix - and then come back to this list!
10 1337/Leet
Someone has to be last on this list, and it just so happens to be the robot Casey meets in the junkyard of Zenith, whom she names Leet. 1337, or Leet, as Casey calls her, is a maintenance bot like Casey who shows her that they're not such a rare model after all, and is convinced that once a bot is outdated, they have no real use anymore besides being raw material.
She's an interesting character because she reminds everyone of the common aspect of being a robot/android in their world and possibly ours; at some point, they all become outdated. She actually manages to convince Casey, who was down because of how Philly had treated her earlier in the episode, that she should become raw material once again. This fails, thankfully, but this bot leaves a mark, and it would be nice to meet more "Caseys" or Leet once more.
9 Jojo
Jojo is an assassin with a height complex. Which makes sense - he looks like a little kid. The fact that Philly makes fun of him on the assumption that he's never had his way with a lady before doesn't help the situation when Jojo is trying to kill Philly, either.
Due to his curse of being small forever, he leaves an impression as one of the more interesting assassins. To help catch Philly, he kills a waitress in a restaurant (Philly finds her and is immediately blamed for her death). Thankfully, the town's multiple Sheriffs ultimately realize it was Jojo all along, leading to his capture.
8 Odin
Odin's your stereotypical knight. He's insanely loyal and will do anything to keep prince Kelby safe (if only Kelby would stop being a brat for one minute). Odin is on this list simply due to the fact that he sticks around the prince, no matter how annoying he may be.
He also attempts to teach valuable life lessons, such as getting your own food, to Kelby in case of emergency. With his no-nonsense attitude, he tries to keep the prince safe, and if the prince is captured, he'll do his best to rescue.
7 9INE
9INE's name is definitely interesting looking, in terms of spelling. Previously part of a group of ronin, he's that character who must always have his booze. Weirdly, even though he looks like a really old man, he says he's only 30 (drinking really did a number on him, didn't it?).
9INE is one of the more powerful characters in terms of pure combative strength, but he has a soft side. He doesn't like to kill unless he really needs to (though he took care of Philly really quick at their first meeting).
6 Dex
Face it: Dex just looks cool. As the leader of Emperor Locke's assassins, she has automatronic limb enhancements and floating claw hands.
She still a relative mystery as to her true motives, but we do know that she's ruthless and furiously loyal to Locke. Her pink hair is something we look forward to seeing more of, and perhaps, some more claw kills through the heart.
5 Hilda
Oh, Hilda. Gone too soon. A soldier on the side of Emperor Locke, she is taken prisoner after losing at the hands of Odin and Kelby's guard bots. It is revealed that she joined Locke's side because she wanted to live, and for her family to live. It's also true that she did not have great feelings towards the Botican royalty, as the history of colonization, war, and betrayal between her people and Botica ran rampant through history.
A really cool part of her character design is her Vitiligo and the fact that she is portrayed as a strong soldier, even while captured. It really is a shame about her demise, because she would have been a great character to follow.
4 Philly The Kid
Gaining immortality from selling his soul to a magic user, Philly is an idiot that keeps wasting his life and dying at every opportunity. Up until he meets S.A.M. and Casey, he's just been wandering through life without a true purpose (until the Fetter suggests he could get revenge on Botica for murdering his parents by continuing to stick with them until the time is right).
Though in most situations, he's a terrible, terrible person (use all swear words to describe him), he does seem to have a heart, well, at heart.
3 Bessie
Bessie is a character in her own right. While she might not have a consciousness, per sé, she is such an integral part of Cannon Busters that she deserves at least this much - she's put up with Philly for such a long time that she's got to have a reward.
Even though Bessie is a relatively old car and is always getting beat up and breaking down, she still manages to stick by the main characters through thick and thin (hopefully Casey can fix her after that last firefight, fingers crossed).
2 Casey Turnbuckle
Casey Turnbuckle is a sweetheart of a maintenance bot. It's not totally certain how she ended up on her own before the story begins, but helping the other main two, and fixing Bessie and everything she sees, are her strong suits. All she wants to do is to fix everything she sees (to the annoyance of Philly) and to continue to be friends and help S.A.M. and Philly.
She's also just so cute. Very, very cute.
1 S.A.M.
S.A.M. the "special associate model" is at the top of this list for being that bubbly naive character in the center of a world of debauchery. All she wants is to find her best friend Kelby, and if possible make as many friends along the way. She's great at annoying Philly (which of course is a plus) with her friendly attitude, and it is fun to see her deal with situations where being friendly isn't necessarily the best course of action.
S.A.M. is also a mysterious "cannon buster," an extremely powerful magical war golem. She is both technology and magic, something which is considered taboo (as magic itself in this world is considered taboo). It will be interesting to see her development as the story progresses.