You are sure right, they all are nice! I came very close to getting a green one too! I would buy the X7xx series for the 4wheel steer, or if I was really sure that I didn't want a loader....... ever, or hydraulics.........ever. I have a Simplicity Legacy, and it has about the same hydraulic capacity as the X7xx, but I have never used it other than to raise the mower deck.. With mine, as with the JD you have to switch from front to rear hydraulics manually, etc., and the flow, and speed are really, really slow.
For mostly mowing, the 2305 adds much more versatility for other things for about the same price. You do lose some things like the collection system is the same, but harder to mount, and perhaps it isn't quite as comfortable, or manuverable........ especially compared to the 4 wheel steer models. Still, in your case, I would look very hard at this model.
The 2320 is a great small tractor. I still think sometimes that it should have been my choice, but my needs are different than yours. I have woods, and rough ground with rocks, and other hazards, I have a use for pallet forks, etc., and I need the extra lift capacities on both ends. If you don't need those things, or other things that the 2320 offer, then the difference in price would just about buy you a nice snowblower for that driveway, etc. Remember that the tractor is the thing that runs the attachments that do the work!
By the way, some would say that mounting/ removing the mower deck on the 2305 seems to be easier, and quicker than it is on the x7xx series too. That is important to me as I get a bit older...
Have fun shopping!!