Magic carpets are supposed to be Longboards with the middle 2.5ft cut out of them. It's not entirely true, but they do perfom in a similar way. Most carpets will be single fin, as the 3 fin option basically turns them into a fat mini mal.
As the two boards go, the carpet is deffo the performance option but it's a slightly different style of surfing thay are suited too. Awesome in waist high winding points, not so great in average beach break.
The mini mal is a good solid option. Nothing to flashy, but it will get you into waves early and give you plenty of speed to make the sections. Stick a decent set of fins on and it will be shaper on the turns.