I personally like Zorin better than Mint. Mint is very dated looking, while Zorin feels more in line with a modern OS. They also try to create an easy experience for non-techie people to use Linux. They need some model to keep themselves going though. The money for pro also unlocks some features they’ve added to the OS and the free software is still free, they just make it easy to acquire it for non-techie people who don’t want to spend time trying to do their own research, or don’t know how to.