I've picked some smaller dual sports, and used models for the bang for buck aspect, all of these would be good beginner bikes;
Lowest seat height, Kawasaki Super Sherpa, a 250cc four-stroke with electric start. Silly name but good on road and decent enough off road to have fun.
Medium Yamaha XT225 (also called the Serow), a 223cc four stroke. Later models have electric start (but would be an easy kick). Made a few more years than the Super Sherpa, so there will be really good prices. Decent off road.
A bit older, and taller, Honda NX250, four stroke 250cc, electric start. More of an on-road bike but will do trails. More power than the others but manageable. The NX has plastic radiator shrouds and a small fairing, which might be easy to damage if the bike is dropped.
Almost any Honda dual sport 250 will be ok, XL250 (really old), XR250L etc, but these are kick start, and only the L model of the XR is road legal. These will tend to be better off road.
A new Honda XR230L will be similar but not usually a good value to buy new. Get any used bike checked by a dealer (often its a good idea to buy used from a dealer and get a short warranty).