Antidote and now PX7 are special to me and they are the only synths I got from the shop without expecting to have to spend that money
Antidote is just a different take on subtractive synths and yeah, it has some small feature additions that do not exist in the stock synths but its mainly the whole package. PX7 totally ninjad me with its patch import. That some DX7 clone was dearly needed in Reason was obvious
The PolySix I could have lived without but I got it anyway as I'm a sucker for that synth. One of my music teachers was totally into it and got so many sounds out of it very quickly I just had to get interested
I also got the Radical Piano but thats another thing ^^ Some RE synths sound outright awful (I look at you, carnivore), theres definitely no use in getting all of them just to have "variety of sound".