I like
Jasper best, because
Jasper Fforde is a fantastic, fantastic author.
Tristan is too popular, and
Julien looks ridiculous. I can't stomach that spelling, for whatever reason; it looks so wussy and sleepy-eyed to me.
Julian is far nicer and would tie with
Jasper as winner.
Any of them would suit a boy with the features you described.
Array
The dogs on main street howl
`Cause they understand
If I could take one moment into my hands
Mister, I ain't a boy--no I'm a man,
And I believe in a promised land.