IMO, there's not much reason to choose the Devour over the Droid unless the aesthetic of the aluminum case is of utmost importance to you. I really like that aluminum case but functionally, the Droid walks all over the Devour.
The Eris and the Droid are slightly different beasts. Eris has no physical keyboard and the Motorola Sense UI - which is pretty, but your updates won't be as frequent since Google has to release the update and then Motorola has to integrate it into Sense. So if you want compact and pretty, the Eris is the winner. If you need a physical keyboard or want a geeky phone, the Droid is probably the one to go with.
The Eris and the Droid are slightly different beasts. Eris has no physical keyboard and the Motorola Sense UI - which is pretty, but your updates won't be as frequent since Google has to release the update and then Motorola has to integrate it into Sense. So if you want compact and pretty, the Eris is the winner. If you need a physical keyboard or want a geeky phone, the Droid is probably the one to go with.