Hello; I have been using four strokes since '91, OS, Saito, Enya Laser HP, and have observed Magnum, ASP, Thunder tiger, and others. I prefer Saitos, but they all can be made to work just fine. Some will last longer some give more power, but they all work. It depends on how much you feel like spending, I suppose. I have an old Saito 45 that has had countless gallons through it with no attention, totally trouble free. I also have an old OS 90 4S that has served just as well for nearly as long. The more modern engines are even better.