Adley is a heck of a player, but for me it is easy. Gunnar would be my choice. I will say it again. Gunnar Henderson is going to be the next Oriole to win an MVP.
I think he'll get some MVP votes this year for sure anyways. AL ROY shoe-in and I'd bet he gets some...
For those worried about catchers though, I think the way Hyde is using Adley GREATLY IMPROVES his chances of being more useful than most down the line. He can be used at 1B most likely down the line also, but rotating him with a catcher like a McCann every other day or 2 on and 1 off and 1 or 2 games at DH and give him a full game off to rest will benefit him greatly I think.
Extend them both, get Holiday up here, have Greyson next year, who is going to be a beast...he looks like a young Verlander to me...same basic build and general look. I think the future is very very bright!