Fal, probably. If they were human, I could easily image them going all out to impress someone on the first date. Flowers, a candle lit dinner, that sort of thing.
Mmm...not sure. Belle?
Argh...possibly Garran? Maybe, if he wouldn't look so grumpy/bored all the time. Banbh is a possiblity too, in a shy, modest type of way.
Rylarth. No question about it.
Callanish. They love fun.
Most tragic backstory
No one in particular has a really tragic backstory. Oh sure, sad things happen to a few characters, but nothing particularly life changing.
Most untragic backstory
Sinister. Created entirely by accident, then ends up being kept as a mascot.
Banbh. I keep changing bits and pieces here and there, but overall he's definitely the most developed. Though, Rylarth is probably a close second.
Not sure, to be honest.
None of them. Saying that, however, Rylarth does have a pretty impressive mane and tail...