If you could pick one walk behind and one push to start with.
I would take the advice from above and get both mowers new from the same dealer. By buying new- you'll know the history of both machines from day 1 and you'll have warranties too.
The question is, what brand equipment dealers do you have close to you? Like within 45 minutes to an hour.
Brands I recommend: Hustler, Scag, Exmark, Gravely. We just bought a Gravely Pro-Walk 36 inch Hydro walk behind mower this summer and it cuts great! We also have the Exmark commercial x-series 21 inch mower and the Exmark Metro 26 inch walk behind- these are both great mowers! A little review for ya, let me know which dealers are near you.
Stryker 6.5x14 Landscape Trailer
Carry-On 5x12 Utility Trailer
Hustler Z4 54
Scag Pro-V 48
Gravely Pro-Walk FLH 36
Exmark Metro 26
Exmark X series 21
Stihl and Redmax Handhelds