Based on that ranking I'd say chances are Karkat will rise to the top spot in Act 6.
BTW sine you liked Tavros/Rufio you should follow this guy:
http://rufiozuko.tumblr.com/
It's the actor who played Rufio doing basically what you're doing in this topic, which is just awesome. He's in Act 5 Act 2 now and everyone is obviously waiting for him to get to the kiss scene with himself and Hussie.