I remember my stepdads one and only rule when I got my first new bike from the dealership. I could have anything I wanted...... If I could pick it up from a lay down.
At 5'10 and 130 lbs my first bike was a 450cc suzuki gts. I wanted a much larger bike but thats the biggest thing I could set right if it fell. I wasnt a happy camper to say the least but I learned later he was right.
Its better to get something your comfortable with and can handle and work your way up.