4 strokes are easier to ride, especially for a new rider. A 2 stroke requires more clutch control (slipping the clutch to keep the engine from bogging). 4 strokes have a more broad power band , which is really an advantage for trail riding, hill climbing, etc. Also in CA. you have to deal with the green sticker/ red sticker issue. 4 strokes pollute far less than 2 strokes. Check out the YZ250F ( four stroke 250, lower seat than the YZ250 2 stroke), DRZ250, CRF 230, XR250
Your choices are going to be limited by your budget, but check out
www.cycletrader.com. Check the ads in your neighboring states, you may find a good deal just a few hours away.
Good Luck