What are your suggestions?
I am not a big fan of Skage and Qyzen Fess, just because of the looks.
Some companions are sexless monsters. Some companions are lizards rather than mammals. Some companions are machines and whether they are pieces of equipment or persons depends on the beholder.
So this question cannot be answered, because too many companions can categorically not attract my characters at all - and that is not a flaw said characters, that just the way it is.
If the question is, which character we find most repulsive from those that would usually be taken into consideration for a mate, the answer would come from my female Jedi Knight and be "Doc". She pretty much shares Kira's (i.e. "Little Miss Uptight" in his words) attitude towards him, though she's more diplomatic about it.