Incinerator or Sunrise/Twilight
Well I have neither a thief nor a mesmer … but if I were in your shoes I’d go with the mesmer. One day you’ll have an uber mesmer with Eternity.
And you’re right about the contributing to the group part.
Mesmers are much better for groups than Thieves. I RP Main a Thief but he got far too squishy and unhelpful so my Guardian is for dungeons and my Mesmers for most PvE.
Though Incinerator is to me a much better Legendary. The GS legendaries are huge flat things with no detail.
Which one did you choose finally? I’m in the exact same spot as you were…
I’d suggest a PM or finding the player in game, this thread is a year old and they may no longer be playing.
(I’m amused I was the last poster in it).