Exactly what the title says. What school of magic do you think a dagonborn is most likely to use? I would say destruction simply because of Dragon's being known to breath fire.

The Thu'um school?
Seriously, I think this should be a school of magic. After all, plenty of Drauger use shouts so there was obviously a time when the Thu'um was more widely used.

I also agree that a lot (most?) of shouts relate to Destruction magic.

Yeah, probably destruction. And a Thu'um school would be pretty cool. Some of the clothes would increase your Thu'um power of recharge rate.

I'd say that a Dragonborn would firstly be a warrior (being a Nord and all). Like said before, he'll probably do good in destruction too.