Dont know if your still in the design phase but here are some ideas 1. Front suspension or pivoting front beam, whichever works best 2. Suspension Seat 3. Easily adjustable deck. Mowers tend to come from the factory with random adjustments. Some cut high from the factory some cut low, it would be nice to be able to adjust the deck to ones own needs when necessary . 4. A deck that can go from closed baffle to open baffle with little hassle. Open decks tend to cut better in not so optimal conditions (John Deere 7 Iron) While others cut best in dry conditions (Exmarks First Ultra Cut Series 4) 5. I like how Dixie Choppers hand both an oil cooler for the engine and the hydraulics. 6. Ease of oil change, both engine and hydraulic. Its amazing how many manufacturers got this one wrong. 7. Foot pedal for raising the deck when needed. 8. Propane/CNG option 9. Fuel guage 10. Tachometer 11. I see a lot of lawn mowers that use a 5gal bucket attached to the frame with a bungie cord for trash. It just sits on the deck and eventually wears the powder coat off. Maybe make something more purpose built for this. 12. Grease-able spindles.