Our family has three lawn tractors in use:
97 JD 325 (smoothest trans)
00 Murray 46" (not smoothest trans, but has foot pedals like JD). Cannot service auto trans.
02 Sears w/Kohler engine and 42" deck (has "auto hand lever operated trans" . Cannot sharpen blades very well, so new blade expenditure is $60 per year.
All have a form of hydro auto trans, as noted above.
Cheapest maintenance is on the JD; it also cost four to six times the others. Parts always easy to get. Have had to take it to dealer for repair only three times.
On the Murray, the deck has been rebuilt twice, literally. Chassis and hydro trans still doing well with no problems. B&S twin engine doing well, but no oil filtration.
Sears does well for light work, 2 acres or less. Excellent Kohler 17HP engine with oil filtration. Mulches pretty well. Deck OK, but does not come off to replace blades like JD, so deck maintenance is less than optimum. This is true for the Murray, too.
Hope that provides some perspectives. I would consider a used JD next time (300-400 hrs or less) before I buy either the Murray or Sears. The Murray has been worked to death on four rough acres, and except for the deck repair issues, can outperform the Sears.