Marathon Plus is a heavyweight but good for riders who really don't want to deal with any punctures.
If you don't mind the occasional flat, then a lighter tyre will ride better and faster.
My Mean Time Between Failures with the plain marathon was about 2 years.
40mm is quite wide for an everyday bike. 32-38 is a good range to use. If your bike has suspension, you don't need the cushioning effect of ballon tyres. Having said that, on my MTB-wheeled urban utility bike, I still run the 1.9" Schwalbe Big Apples on my rigid Al bike.