I vote for William, as that is my DS's MN and is also my dad's name so of course I love it! For other suggestions- do you have any dads, grandads, uncles, etc that have names you like? I've always had the philosophy that a MN should be meaningful in some way so an homage to a family member could be a place to look for name suggestions...
Re: MN for Landon
That being said, Jay sounds great, too, and I love that it's a family name.