Just finished the vMSA on my sorc after finishing it on my magicka Templar yesterday. I have to say it's a lot easier as a Sorc at least in the beginning. Maybe Templars can perform just as good if you have a lot of practice in the arena.
For PVE healing most of the groups prefer a Templar because of the stamina return through shards and repentance. In my opinion the NB is the better heal because you can deal more dmg while healing (funnel health, sap essence). For a pure DPS I would also take a NB because of the utility, even though sorcs deal more single target DPS (in short fights).
So for pure healing take a Breton Templar, for pure Arena and DPS take a high elf Sorc and if you want to be flexible and play all roles pretty well (even tanking) then role a Breton NB. I haven taken my NB to the arena yet but it seems to perform good (world high score in VMSA is hold by a NB atm).
I hope that helps.
I'm torn between nb and Sorc arm. Since it doesn't seem like there's a huge disparity in dps, what about alternate roles? Nb healers seem awesome but what about a sorcs alternate role?