The L and LT series only have a 2 gallon tank. At the 1.3 gals/hr that TimberXX said, and 8 - 10 hrs pr week, you're going to be filling up that tank 4-6 times a week.
I like John Deere, and have one of their CUTs, and I liked the finish on the L series better than on Husky/Craftsman for example (not knocking either one). I came close to buying a Husky myself, but ended up with a great deal on a new leftover 2004 Toro. It ended up quite a bit more than the Husky, but I fit better on the Toro and the Kawasaki was pretty smooth and quiet, plus the Toro is several hundred pounds heavier and is built like a tank.
My point is that you might want to look at some other brands than JD.
Your decision might also be influenced by how long you want to keep the tractor. If it's a short term business you have, then a lighter tractor like an L might be a fairly economical means to an end. If it's going to be a consistent thing, and you're only cutting grass, then a ZTR might make more sense.
The old saying: "You get what you pay for" still holds true.
Good luck!