I have about 5 acres to mow. It's steep in a couple of areas and I also have trails through the woods. I was faced with the same problem as you. I really wanted a zero-turn for its speed, but that was the only advantage. Then when you factor in my lawn is not smooth, and I could not go really fast, that advantage was moot.
Zero-turns are really a one trick pony. They cut grass better than a tractor and are much faster. However, they are not that great on steep slopes or uneven terrain.
For these reasons I choose a tractor. I wound up with a Kubota
BX2680. It mows really good and will go places the zero-turn won't. The added advantage is, can use it year-round for other chores as well.
Dave