All the tractors you are considering are great units! Weight wise, the Kubota
B2630 is a closer match for the 2520 than the
B2920. It is available with a Kubota QC for the Fel, but I think that only Kubota pallet forks are available for that. There is a bigger variety of attachments available for the JD fel QC. The
B2620 is cheaper than the
B2920, and will run 4' implements just fine in that size tractor. The added hp is nice if you live at altitude, or want extra oomph for a
chipper, or something. The Kubota front frame mounted QC is nice, and is easy to install for the
B20, and B30 series. A 60" blade is available for the
B20 series, and a 60", or 72" is available for the B30 series. Prices tend to be area specific, so I can't comment too much on them. Dealer service, and attitude is important.
Some folks have mentioned that the fel mounted blades can be finicky about dump angle, etc., and some others have mentioned that it is difficult to use a frame mounted front blade in float mode on gravel, or grass. Your mileage may vary. Both can unload the front end, and make steering more difficult, and that perhaps may make steering brakes more useful. With the Kubota you need to use your left foot on the go pedal, or use the cruise, with the Deere you need to use your left foot on the brakes........ pay your nickel, take your choice.
I wouldn't like either a front blade, or snowblower that was narrower than the tractor. Some folks have built extensions on both that work.
I think the attachments for the Kubota are better matched to the tractors than the Deere ones are. I like the QC fel pin system on the Deere's a lot, and like the position control, and steering brakes on the left. Seems we can't get everything on any tractor.
Enjoy!