None, they all suck.
Yamaha TTR 125
im not sure about that but i can say that a 2 stroke 125cc is faster than a 125cc 4 stroke and probably 200cc too. a 125cc 2 stroke would throw you off the back if you cant handle it properly, where as the 4 stroke wouldn't scare the living daylights out of you
for a 4 stroke: beginner level 2 stroke: experienced they are huge
RX 2-stroke
Kawasaki is the best 125cc dirt bike. Hopefully this link will helps you.
A KTM 250sx is the worlds fastest 250 2 stroke dirtbike.
The size or displacement of the engine, 50cc versus 125cc.
A 125cc dirt bike typically runs on regular unleaded gasoline with an octane rating of 87 or higher. Some models may require a mix of gasoline and two-stroke oil if they have a two-stroke engine, while four-stroke engines use straight gasoline. Always refer to the owner's manual for specific fuel requirements for your bike.
A 125cc four-stroke dirt bike typically reaches speeds of around 50 to 60 mph (80 to 97 km/h), depending on factors such as the rider's weight, terrain, and bike modifications. Four-stroke engines tend to provide more torque and smoother power delivery compared to two-stroke engines, which can affect acceleration and overall performance. However, the actual top speed can vary by model and manufacturer.
there are no age limits for dirt bike. but there are recomendations for size
you would need about a 125cc 2 stroke
it is 33.1 in