I can tell you that I find very little actual difference between the actual work performed by the TC24 and the B2910. The REAL difference is in the PTO powered category, if you need to run larger PTO powered implements then the B2910 or DX29 is a better choice than the DX24.
I run at rear mount 60" snow blower and the TC24 has no problems with that, but I admit that I have not faced a blizzard with it yet. The 63" front blower was double the price and my drive is short enough that I could not justify the added cost, despite the added convenience it provides.
The DX24 will run a 60" mid mount mower and the mower deck is built like a tank, very high quality. I switched to a MMM this summer after using RFM for many years, and I am very happy with the results of the MMM.
Based on your tasks, I think the DX24 would be MUCH better than the X585. The DX24 will be a better FEL machine than the B2910 because while the loaders are equal, the DX24 turns tighter and has substantially better visibility. The DX29 is much stronger in the loader department than either the B2910 or the DX24, it would likely be the best for plowing and pulling a box blade because it would weigh the most of the 3.
The DX29 and the B2910 would likely be about equal in heavy mowing because both have similar PTO hp. The DX24 will do heavy mowing, but it will use a smaller mower deck that either the B2910 or the DX29.
How much are you actually mowing? Is that area open field or are you mowing around obsticals? Your profile has you with 10 acres, so I'd say you could easily use a 30 hp machine, but you could also use the 24hp machine. You may find the 24 a bit cramped compared to the 30 hp tractors. See what fits you best. None of the 3 will be a bad choice.
IF it was MY money, I would go for the DX29 or DX33 if the cost was similar.