Great question. I think a big part of it comes down to preference.
Some people like Online, "the cloud," and the advantages that come with it (being able to work remotely, easier access, no storage on your hard drive, etc). Others want their data stored locally and need the greater functionality of Desktop. There are different flavors for different types of users with different needs.
CPAs and accountants tend to have a preference and, from a compatibility standpoint, it's important to consider it if you want to keep working with them in the future.
But at the end of the day, go with what works best for you. Desktop as a product isn't going anywhere and regardless of the volume of users on one over the other, you should go with what meets your needs.
