Does he know that Elias is the Latinized version of Elijah? You both like the same name! :) I think this is the name to fight for. They are so similar.
It's too bad he won't come around to Elias. It's so close to Elijah (and I personally like it a lot more than Elijah). Rowan is almost the compromise name it sounds like, what about some other names that sound somewhat similar, maybe he'd be more on board with them, such as Ronan, Roland (great name!), Nolan, Owen, Ewan, Olin, Bolan, etc etc etc.
I do agree though, your list is awesome, his is not so awesome, though I do like Zane from his list. But from your list I like most of them (not the biggest fan of Tristan or Apollo, but the others are pretty great). Though he does seem to like names that end in 'n' (Brennan, Landon, Jayden (even Zane ends in the 'n' sound)-- and preferring the two 'n' ending names from your list too-- Rowan and Tristan). So perhaps you can find a few more options you like that end in 'n' or the 'n' sound? Maybe he'll like some of them more.
Roland would a great option, seems to have qualities he's looking for too.
Lionel (another 'Leo' kinda name maybe he'd like?)
or the many other Elijah variations--- Elian, Elliot, Eli, etc etc
Tristan is a good compromise. I could give a nice, descriptive spiel about how awesome this name is if you need some more convincing.
Brennan is also a good name.
That's a tough one!! I like the suggestion above of finding names that end in "n" that he may like.
Leonel Rowan Elijah?
Elijah Leonidas nn Eli or Leo or even call him Elias if you take "Eli" from Elijah and then the "as" from Leonidas? Then you both get "your way"? This sounds like a clever compromise to me!