Oooh I can think of so many

I'd like to see Darren Carnall or Richard Roe as Link Larkin as I think they're both amazing dancers. Perhaps Lee Mead or Joseph Connor as Fiyero. James Byng, too short probably but because of the emotion he put into his songs and acting when I saw him in LOTR, I'd kill for him to play the Phantom one day. James Bisp as Jack in Into the Woods because he was so sweet and has an utterly gorgeous voice. Greg Bradley as Jekyll or a lead in WWRY because he's got such a powerful voice.
Hm...looking at that, mostly I'd like to see understudies/ensemble members I've thought were amazing, in my favourite lead parts lol