I think Oliver is the nicest and goes the best with Noah.

Oliver Byron
Oliver Jack
Oliver Blake

I like Xavier pronounced Zavier rather than Exavier. I would even consider spelling it Zavier but I guess it might be annoying having to tell ppl how to spell it.

Xavier Ross
Xavier Isaac
Xavier Elijah

I'm not huge on Zachary. I really don't like the nickname Zach.

Zachary Spencer
Zachary Eden
Zachary Leigh