Unfortunately the Kubota website does not have a good way to compare tractors that are not in the same group such as
B2620 to
B2920. The only thing you can do is click on specifications, then go to the bottom right hand corner and click on the PDF file and print it out for each group.
The B2x20 group are smaller framed basic tractors with 3 cyl diesels. The 2320 normally comes with a slightly smaller FEL. The 2620 and 2920 are the same except for HP. I live on 3 acres which is basicly a big yard and I think they are a perfect size for the projects I do and mowing on that type of property. I also use it to maintain a 400+ ft rock drive with a box blade and clear snow in the winter using a rear blade and FEL. The engine is smooth. It will do a lot of work at fairly low RPM. We also have 12 acres of recreational property about 25 miles away so I have to trailer it there which is part of why I wanted to stay with a smaller size. It is ok for that property, but some of the things I get into there would be better suited to a little larger tractor including a lot of mowing with the brush hog, dragging trees to brush pile, trying to clear areas, etc.
The
B3200 & 3300 are larger framed basic B tractors with 4 cyl engines. They have the 1/4" valve like the B2x20 group. Pretty much the same tractors, but the 3300 does not have a mid PTO which saves some money. So you would not want to choose a
B3300 if you are thinking about a MMM or snow blower. If you read in the Kubota forums, you will see discussions on the vibration in the 4 cyl kubota engines when they are at PTO speed. I would suggest when you test drive it, you make sure you get it up to the PTO speed yourself and see if it is something that would bother you. Most of the work you do, you don't have to have it running that fast, but for mowing, you need the RPM's up.
The
B2630 &
B3030 are the same tractor but the 2630 is a 3 cyl 26 hp and the 3030 is a 4 cyl 30 hp tractor. For some reason, there seems to be few complaints about vibration in the 3030. To me, the biggest feature difference in these premium tractors vs the basic tractors is the position control mentioned in a previous post. As I said, this would make life better that the 1/4" valve system if you are going to be running a brush hog a lot. If it is a once in a while task, not such a big deal.
In the end, no amount of reading specs or these threads will substitute for going and sitting on some and test driving them. Any of them should easily last more than the 10 years you mentioned with basic maintenance.