You simply have to do this while visiting Essaouira! We didn't try any of the other companies offering quad bike rides for reference, but Palmaquad was just great. Really professional, adaptive to our skills (which of course are impeccable ;) ), and very helpful. They even gave us a ride to the Medina after we were finished. We went for the 2 hour dunes ride with 125cc bikes, which was great. If you are riding the dunes, I don't think you need to go for the 300ccs, as the 125ccs pack quite the punch when the speed limitation is lifted. The ride itself was very versatile and challenging, with rising difficulty as the trip progressed. At the end we had a non-intentional free safari as well, passing a lot of dromedaries, cattle, goats and the like. Highly recommended!