The 2305 ROPS is shorter than the 2320, well, actually the 2320 ground clearance is higher than the 2305, so the 2305 ROPS doesn't hit the garage door (at least mine doesn't).
If you'll be grading the house site, then you probably want something bigger and more earth-moving friendly. Otherwise, the 2305 seems like a good bet. On moist clay soil mine can still leave tire marks if I'm not careful (even with turfs), so anything heavier will just add to it. The 2305 is made for homeowners that want to (1) cut grass, (2) landscape, and (3) find other things to do. The 2320 is the same machine with a higher ground clearance for off-road work (and some spec differences that you probably wouldn't notice). The 2520 is where you start shifting the priorities away from grass cutting and more towards heavy duty use - it's not near as friendly maintaining the yard as its two smaller cousins.
If you want the hoe, how much will you use it and how quickly does the project need to be finished? If the answers are 'a lot' and 'quick', go with the 2520. Otherwise, the others will work if you allow the time necessary for bigger jobs.