What should my next dirtbike be?

I'm 14 5,6 and 140 lbs. I'd say I'm a very good rider. Ive had 4 strokes and 2 strokes. the biggest 4 stroke I've had was a crf150r . the biggest 2 stroke was my 1st and current dirt bike which is a yz 85 . its bored out to 125 believe me everything was done to it. I'm looking for a bigger bike. If i get a 4 stroke would a yz 450f be huge for me because those are professional bikes. and if that's to big how about a 250f or 2 stroke 250 ?I'm just stumped and i need another opinion! Thanks.