I already suspect Tuchel is higher on the list than we think, I don't think Howe would leave because of his setup currently. Tuchel fits a lot of needs, proven across multiple leagues especially in the PL, is able to play different styles, is friendly with English players (something Ratcliffe has wanted to increase), has worked with tough board and fan expectations, doesn't have to run transfers either. He'd probably be better than any of the up and coming coaches out there. What we need is stability and Tuchel can provide it for a few seasons. It could be troublesome with the Rashford question hanging over the club though, if Barca says no to his wage demands, Rashford could end up coming back if Tuchel wants him to stay
Luis Enrique would be a pipe dream for me but even then there's questions on if he could work in the PL