Honestly, both could be good, the Templar would likely work like a Battlemaster in terms of Arm shields, that being said, her crit lay out sucks. Granted she's got about 40t to work with for pod space, but tons of locked up locations due to iEndo, she is how ever an efficient 85t in terms of engine to speed ratio and, should she get a JJ varient, 1t Jump Jets.
For the Sunder, I'm not sure how well those arms would protect the ST's that are vunerable due to the 360 iXL, her major advantage over the Templar, comes at the cost of weight efficiency. The Sunder is locked to standard armour and structure, meaning she is cavernous in terms of cirt space, but lacks both hard points and tonnage to effectively use all that free space.
How ever should the Sunder get a good face lift,I think she would be a serious contender for best IS assault, just as I think the Templar could get that title. I think this is a very even match up, between these two.
Edited by Metus regem, 02 February 2017 - 11:05 AM.