3. Most importantly, both the developers are responsive, however at least from what I've seen in this thread, Tigzy from UCheck is more open minded to suggestions and feedback without locking horns with competitor software's.
While I gladly use SUMo because of it's large database, I found the author of UCheck to be dedicated to his program and threads, and not de-railing posts in competitors threads like this by promoting their own products. Along with this the only time that I've probably found SUMo in bad taste is when it started bundling adware/malware in the past. Since the portable version was not having this issue I kept using it.
While it's up-to the author to decide whether to support 1K software's or stick with popular software's that most users tend to install, depending on their business strategy, SUMo is more useful for people (the geeks) who browse and install various softwares on their system,, UCheck is suited to general surfers who doesn't install anything other than the popular stuff