Pat, if the primary use is mowing, I think you will be happier with the B2920 though you may not need that much horsepower.... really.
The drive over deck looks like it is much easier to R&R and I think you will find that very important if you want to do other things with the tractor. You don't say how much land you are maintaining, and that could make a difference. The larger B's are actually quite nimble without the loader on, but the loaders do stick out quite a bit more, and that is important in tight places. I'm the odd duck, and like the B2630 the most of the large B's because it runs so smoothly, and is a pleasure to operate. It is no where near as popular as the B7800, or B3030 though. I do like the position control, front quick hitch, and 3pt hitch setup much better on the B2630. I can certainly see going to the B7800 if you are at some altitude, or want to run a 5' rotary cutter in thick stuff, or hilly terrain. The larger B's have a somewhat more stable footprint, especially with the wheel spacers. I think you need to evaluate the size of implements that you want to run, and the amout of land you need to cover, and then size the tractor accordingly. Have fun!