My favorite troll is Terezi, but I might be a bit biased.
1. Terezi
2. Karkat (Karkat is just hilarious)
3. Sollux, Kanaya, Gamzee, Feferi (neutral about)
4. Nepeta, Tavros, Aradia (annoy me)
5. Eridan, Vriska, Equius (really annoy me)
At this point though, there's almost nothing that Eridan, Vriska, or Equius could do to redeem themselves. Aradia is just boring and depressed. Nepeta is just annoying (just an average furry then). Tavros is just a whiny bitch. Trolls in 3 don't particularly annoy me. Karkat is just hilarious. Terezi is a great character.
As far as best roommate goes, I don't know. Definitely not anybody in 5 or 4. Well, Aradia wouldn't be as bad as the others. Tavros would be annoying, and Nepeta would just be weird. Feferi would get on my nerves after a while, and Gamzee would leave his Faygo everywhere. Sollux could blow everything up at a moment's notice, but bees are annoying. Karkat would be annoying, constant yelling. Terezi would be... interesting. But I don't want to get hanged or something
Yeah, they'd all be pretty terrible roommates, but Terezi would probably be the best. Coloring on the walls would be annoying though. But I don't really care for aesthetics at all.
Oh wait, the kids too? John would be annoying, too many pranks. I have enough irony in my life already, so no Dave (plus I'd have to deal with Lil' Cal). Rose would probably end up sacrificing me to the eldritch gods or something. Jade would be annoying, randomly falling asleep, and shooting random things. I just find all of the kids really annoying. I like Dave the least, and John is second.
Kanaya or Nepeta. Kanaya would be really nice and helpful I'd imagine, and Nepeta would just be cute
For Kanaya, one word. Twilight.