"Since version 3.0, QupZilla is no longer developed and new version are released with Falkon name as a KDE project."
My 2¢ after playing with #Falkon for a little bit:
1. Falkon might be more resource-efficient on a Qt-based desktop than others -- or if you run a lot of Qt apps in general, particularly those that make use of #QtWebEngine.
2. Falkon's tracking protection is a bit limited, but at least it doesn't phone home out of the box -- which is a problem that both #Chrome and #Firefox have, though you can at least disable this in Firefox.