Cosette was the easy choice just cause she's new and I'm not attached to her yet--I wouldn't care too much if she were written off.
I personally am bored by Pintsize's antics most of the time (my reaction whenever there's a robot-only update is "oh dammit, a filler comic"), but I don't think he could go without QC losing a rather major part of what it is. So I wouldn't really go that route.
I would actually.... kind of like it if Hannelore or Angus were to disappear. I'm very nonchalantly disposed towards Hannelore--I don't dislike her, but don't particularly care about her either, and all the adoration of her on the forums (and the way the comic itself seems to demand that we LOVE HER) kind of pushes me the other way. I'm not saying I'd want her spitefully gone, but I might well find QC refreshing without her and the by-now predictable "Hanners-is-creepily-cute" stories.
Angus? I LIKE him. I really do. But not as much as I liked Sven. So I want more Sven. And I find that as a couple, Faye and Angus...don't interest me as much as they did before they were a couple. I found Angus more fun before, when he was pestering Faye than being smoochy with her. (And I cringe saying that because I'm against the idea that you must maintain UST in fiction and that happy couples can't be fun to watch/read about.)
I might not mind if Tai disappeared, either. She's fun and I actually would LOVE to see her pursue Dora (and have that be more of a storyline than Dora just saying "thanks but no thanks"), but she's enough of a tertiary character that if she were written off, I wouldn't be particularly heartbroken.