Treek is not really a companion, she's an over-powered crutch with an attached sequence of conversations and some annoying noises that give you an incentive not to use her. Make up a few legacy Aim sets with your GSF armor and she's good to have in your back pocket for some situations, but I'd far rather run with Temple, Vette, Mako, Corso, Ashara, Gus, Scorpio, or Xalek.
You know, BW probably has stats on which companions people use the most. It would be interesting to find out who are the most popular companions. Maybe even have a competition -- designate a week and award the "Ms./Mr. SWTOR Companion" title to the companion who gets used the most during that week. I'd spend the week grinding dailies with Vette.