Be a big name at Leeds, with a coach like Bielsa and it could be Real Madrid next. At Liverpool or Chelsea, he'll get no game time, will play a bit part, and in 4 years time he'll be off to a Villa or similar.
If I was his agent, I'd have his eye and my eye, on his next move, not this one. Earn a couple mill now, then make 10 mill next move as the agent to a big CL side. That depends on player loyalty to an agent of course, which I don't know much about to be fair. Do you stick with one firm, or chop and change like a temp contract?
I think he's worth 25m - stick some BS add ons in there, like qualify for CL, he's gonna play for England and that doesn't help us, so avoid that one..