I am currently at level 51 Immortal and it is Vette all the way for me. I have a lot of time tanking on that "other game" and maybe I am making a bad assumption, but if you are having survivability issues without a healbot then it is pilot error/inexperience. All of your CC is defensive CDs as well. If you are using all of your cc and standard defensive cds you should not be taking much damage. If you have blown everything in a pull (that must have been one hell of a pull) you shouldn't have but 1 minute until almost everything is off of CD. Any pull that isn't a boss or a gold mob (sorry I am not familiar with the lingo on this game yet) shouldn't require more than a CC. I don't have to heal up much, I rarely drop below 75% health (typically no more than 95%) and if I do it is because I played poorly. Not that I haven't died, but it is always my fault or because I accidently summoned a world boss. (So I guess that wasn't a lore object). Vette is the better dps because she is ranged so she inherently takes less damage. BUT, you have to front load your threat or you will be chasing/mob hopping. Just my two cents.

2V-R8 is the best companion.