Patton's troops were scattered all over France because the inability to land enough supplies to keep generals doing a great job from doing their job and it kept and was used the excuse by generals who did a crappy job and that is where I would put Montgomery. In another post on this thread someone made a comment about Churchill wanting to change D-Day as an example should really watch the movie Churchill and read up on it very enlightening. Yes he made mistakes but he also for the most part knew what was needed to keep Britain fighting and keep its people motivated.Miles Dempsey was picked by Montgomery to lead 2nd Army Group he was familiar with the planning for Overlord. He was reckoned to be very easy to get on with and popular with Eisenhower. Plus whilst everyone goes on about Pattons dash for Germany Dempseys 2nd Army Group advanced 200 miles in 7 days and werent scattered all over France like Pattons units.
Alexander, he was very much liked by the Americans and also by the British politicians. Only point of critique of Eisenhower on him was that he was too much of a "yes" man towards his .subordinates.
Too much of a Yes Man to Churchill as well. Patton pronounced the SHINGLE operation a suicide mission, Clark recommended it not be executed, Eisenhower thought it buried when he left SACMED for SHAEF. Wilson had reservations. But, Alexander would not say 'NO' to Churchill and ordered the job done.
Under Ike's direction Shingle was already well advanced... Thus another gets credit for a long-layed plan which developed under Ike. But the truth eventually 'will out'...