There is a big difference betwnn a 4 stroke, and 2 stroke. More than sound. A 2-stroke you have to geep the RPM's up, on the throttle, not that much bottom end. But it gets the job done, and it is lighter. And less maintenence. A 4-stoke is a wider powerband (more controlable power) MORE bottom end, and it is heavier. But there is alot more maintenance.(to name some differences)
I would say a KDX200 or 220 2-stroke trail bike. Great for trails, and can be ridden on the track, and is almost like a 4 stroke. Good power, all around a good bike. If you didnt like that then a 125 2-stroke, or 250 4stroke.