I don't think there is an official group named FOFDP (fans of fake Dr Pepper), but after viewing the Faked Dr Pepper website, I'm concerned that there isn't.
Who would have known there are more than 100 versions of the Waco, Texas, soft drink? This site contains a collection of the drinks and a simple taste rating, from Dr. Riffic (five Dr Pepper cans) to Dr. Rush (described as "taking a handful of grass and dirt and drinking it").
There are very few on the list I've actually tried, but I would agree that Dr. Chek is pretty good. Mr. Pibb, the most well-known imitator, ranks fairly low, but it's replacement, Pibb Xtra, finished at 18th.
I do enjoy a Dr Pepper every once in awhile (I think people who drink it all the time are psychotic!), and most fake Dr Pepper isn't too bad. But more than 100 types? I'll drink to that!