The CYO flavors aren't really different. They add a single flavor (e.g. Lorann's) to nicotine, PG and VG. Other vendors do the same. But Tasty Vapor's is generally less expensive.
The difference is in the premium flavors. All of them contain at least 5 flaovrs, mixed in a combination Geoff worked out. These are unique to Tasty Vapor. Even if another vendor has created a flavor based on the same real-life food, it's going to taste different. If you like Geoff's take on these flavors, you become a Tasty Vapor fan.
I have tried other vendors. There have be a couple whose products I truly disliked. As for the others, I generally find that if I order 4 or 5 I will really like one and sort of like one more. With TV, I will really like 3 and sort of like the rest. It therefore just makes more sense for me to try all TV premium flavors before branching out again. (And, as I have learned the problems caused by having too many flavors in-house at the same time, and I adore so many TV flavors, I can't imagine buying anything other than very small bottles from other vendors in the future.)