I'm probably going to try goolock first because I'm curious to see how they implement a great old one patron, especially since they suggested there would be some sort of patron interactions, although I suspect that fiendlock will end up better fleshed out in that regard
I'm not confident they will add much in the way of patron interactions. They have made it clear you will be able to invoke your patron for help during some checks and such, but I doubt there will be much more than that.
I would bet serious money for instance you won't be able to pick a specific patron or physically interact with it in any way(i.e: the patron won't actually show up in the game or change anything of importance). They have a lot of resources but not that much. It will be just a voice in your head on some specifc interactions you can ask for help and that is it. Won't even have a name or specific identity beyond "archfey" or "fiend". The exception is the Wyll origin off course.
Plus it will be very schizo having another noncorporeal entity interacting with your mind besides the tadpole. Convoluted even.