I've had an E-1 and bought an E-5 for a friend. They are simple, no frills cues that play well. Great beginner cues.
You should pay less than 200€ for the E series since they are rather old and discontinued by Longoni. The M-1 is one of the Mika Immonen series and also discontinued. A possible upgrade path is buying a Longoni Master shaft (with inlays in the shaft) or, of course, any aftermarket shaft.
I would say all play very similar with the only difference being the visual appealing of each model.