What are some good fast dirtbike models from yamaha, honda, and KTM?

What are some good fast dirtbike models from yamaha, honda, and KTM?

For reliability get a four stroke. The brand doesn't make much difference. All of the major motorcycle companies make excellent bikes. I would consider what dealers are near you and which of them has a good reputation in their service department.

Any of the ones I'm riding at that particular moment.

You have a cc range?
Want to use it for racing and/or trail? Or one or the other?