I can only tell you what my experience has been.
I bought an ugly green and yellow Yard Man four years ago for the simple reason that it was the only hydro mower I found that my 13-year old daughter could reach the pedal on. My neighbor and good friend bought what I really wanted, a John Deere, the same year. We both mow about 1.25 acres. Mine is 17-hp twin, his 15-hp single. Mine 42" deck, his 38" deck. Mine has pressure lube with filter and I may be mistaken but I don't think his does. Both are hydro. I gave $1600, he gave more than $2000. My blades cost half what his do. I have had no repair cost other than blades due to hitting a stump. He has bought blades, muffler, starter, a switch for pto, at least one bearing on the deck, and now the seat is coming apart. A new seat cost so much that he is sitting on a foam cushion when mowing. I have been out $0 on repair, except for blades, and he over $500. My mower has been available for use any time that I wanted it. He has borrowed mine several times while his is in the shop. This is not what we expected when we bought our mowers. This may not be typical for the Deere or Yard Man, but, based on my experience I would buy another and I suggest you look at one of these mowers. I have seen them advertised for $1500.
Stay away from Craftsman. I have owned them and had good luck but know three in the neighborhood who have had bad luck with 3-4 year old mowers. They were told by the repair men that some models had major problems. One guy finally took his back to Sears and demanded his money back (don't know how that turned out). They may have the problems solved by now.
As for replacing the engine on the Snapper, been there, done that on my mothers. Expect to replace everything else, clutch wheels, axle, belts, etc. within a couple years at the most. We used one junker to keep other 'good one' running for a while until it got to the point we were working on it more than using it. Eventually convinced her that she had spent enough on the old one to buy a new one and still didn't have anything to mow with. Of course she bought a new Snapper exactly like the old one because she already had all the spare parts. She mows around five acres weekly and is 78 years old.
You can get a gem or a lemon in any brand. Dealer service is the deciding factor to a lot of people but never seeing the dealer after buying is the best.
Good luck.
Smith