I actually felt the other way round. Mesmer was terrible until 30 and got much better after. Also have to disagree on the elite skill: few felt so supportive as those of the mesmer, especially since the sylvari gets the seed turrets including 3 seconds of invulnerability in addition to time warp and mass invisibility.
Personally, I regret making my starting char a human female warrior, as I'd rather have her be a charr. I wanted all armor classes with humans (achieved in Necro, Thief, Guardian) and really liked the Charr storylines and general attitude and "flair" so that would have made sense. No regrets about the warrior class itself though.