I started out with a regular riding mower my first year out. I was
part time, mowing six lawns per week, but by August that year I
had 14 lawns. I sold my riding mower and bought a 48" eXmark
lazer z hp. It fits in tight spots, mows anywhere a walkbehind
does, except steep hills and doesn't take up any more trailer
space than a walkbehind. Don't limit yourself with a riding mower. They are too slow and un-productive, I think you will regret investing money in a riding mower without being able to get it out in a trade-in.
The moral of the story is, think about the future, how many lawns
do you want to do and will the equipment you are looking at support that goal. Good luck.