Sebastian or Tristan?

I am having a hard time deciding between the name [name]Sebastian[/name] or [name]Tristan[/name] for my third son.
I think I like [name]Sebastian[/name] more because our last name starts with a T. my husband likes [name]Tristan[/name].
My other two sons are [name]Gunnar[/name] and [name]Gavyn[/name]. I also have no middle names at all.
Which name do you think goes better with [name]Gunnar[/name] and [name]Gavyn[/name]?

If your last name starts with T then I prefer [name]Sebastian[/name].
It’s a good, strong name.

[name]Even[/name] without knowing your last name starts with T, I would have chosen [name]Sebastian[/name]. I love that name.

Another vote for [name]Sebastian[/name] by me!

[name]Sebastian[/name]!

Another vote for [name]Sebastian[/name]. FYI- I recently purchased yet another baby name book and it states that [name]Tristan[/name] is forecasted to become very hot in 2011.

[name]Sebastian[/name] - I love that name!

I love both names, but the fantastic nn [name]Seb[/name] does it for me, so I’d pick [name]Sebastian[/name].