Well, here's my trip down memory lane (iron sets only) :
Wilson X31
Wilson GE1200
* Ping Eye 2 (3 sets)
* Ping Eye 2 BeCu
Ping G2
Ping i5
* (Florida) Ping i20 (3 sets)
Ping S55
* (Idaho) Ping Anser Forged 2011(3 sets)
Ping Anser Forged 2013
* (Michigan) Ping iE1(4 sets)
20? Yikes! Of the 20, I still have at least one set of those sets marked above with an asterisk.
I currently game the Ping IE1s in New York, but I've got 3 sets of clubs that "reside" out of town with friends or family for when I visit.