Since you are from morocco the selection is pretty limited (salam choja, lebes?), i know yamaha dealerships are all over the place.
I plan to get a motorcycle myself (located in Europe), i checked everything and although the KTM bikes are all pretty sweet i will go with the yamaha xt660 supermoto version, its a rock solid bike, needs nearly no mainteance and 50 horsepowers out of 660cc is enough, over here its 6000? new from a yamaha dealership.
Maybe look up to that, i know that used motorcycles/car are crazy expensive in morocco so if you could afford it maybe go with a new xt660 and keep it until it falls apart in 10-15 years.
If you want a 50cc i guess you will go with mbk booster or mbk stunt, last time i was there they were all over the place (mbk stunt is new about 60% of the price of a xt660 though).
regards