What is the best dirt bike for trail riding only?

im 16. 5 foot 9. 140 lbs. i have a yz 85 at the moment it is a 2 stroke and i can rip on it. it is too slow and too small for me. looking to get a bigger bike. either a 2 stoke 250, 125. or a 4 stroke 250f, 450f. no trail bikes im a good rider and like to have a good time on the trails. i go fast. please help me out