In a 3-4, probably Mingo for his raw athleticism and upside as a rusher. He's only played end for like 2 or 3 years. He was a linebacker and a safety at points during his high school career. LSU would drop mingo back into coverage a lot and he did it well. He's not big enough to hold up as a 4-3 end but his first step explosion is going to be a TREMENDOUS asset for him when he gets to stand up a little bit off the line of scrimmage. He's incredibly fast out of his stance.
Montgomery, I think, could be a solid 4-3 end and a serviceable rush linebacker in a 3-4. The problem with him at linebacker would be limitations in coverage. He reminds me a lot of Chandler Jones that New England drafted last year. Not a superstar but a solid player in the league.