Go with the Deere Z425. Separate pump and motors, very good cut quality (with the 48 in. deck), and in most places very good JD parts and labor support. I have one, like it alot, and it's cut my mowing time in half from the riding tractor (like all ZTRs do). I have the double bagger system on mine. I've had zero problems in 3 years of ownership. Only thing negative is that grass collects under the deck pulley covers so you need to remove the covers and clean/blow out once in a while. Oh, powered deck lift would have been nice too but that's normally found on the higher end models.

Thanks for the input larso1. I know what you mean about the deck pully covers, same problem on my current Simplicity. How is the deck lifted and lowered...with a manual crank? Is that a problem? My current tractor uses a crank to lift and lower the deck and I dont have any problem with it.

No, the lift lever is not a problem. I guess I'm getting so used to powered accessories that I almost expect them anymore. You do have to hold the deck raising/lowering lever (holding up the weight of the deck) while readjusting the height adjustment pin location, but it's really not a problem.