Visiting the UK Gencon with a bunch of mates (about seven years ago), was what got me into collecting. Suddenly, my youth was there on display.
Still, once it moved out of London, I didn't go back (I try to avoid leaving the city if I can), so I can't really complain. Some of the smaller cons here are really fun, but I don't think that the gaming community here isn't large enough for the UK Gencon as was. Perhaps it could have metamorphosed into a different kind of con - a smaller, maybe more specialise con, but then it wouldn't be Gencon.