Well for me... it was really the 2009 Ace Race (not the disc but the actual Ace Race). Discraft did the Focus putter that year... needless to say I was less than hyped for the event (I really wanted the Stalker for the Ace Race disc that year) but I ended up falling in love with putters after that day. I am a putter thrower now... I use my Challengers on a lot of holes that, some might say, are mid range or fairway driver holes. That Ace Race changed my game! So I say thanks also to Discraft for coming up with such a great idea for an event and a pretty nice putter too!
Sure enough the Buzz is one disc I wouldn't want to be without. No matter what discs I try, I always end up going back to the Buzz.
But the disc that changed everything was the original Cyclone. Premium plastic in a premium design I can't tell you how many times I saw someone throw their first Cyclone and at the throw their longest drive ever. No longer the longest disc, it still holds a place in my bag and in my heart.
Flat top 'Rancho' ROC (DX): I am driving with this disc more & more because of it's long, straight flight with minimal fade. Love it on long downhill shots. It just flies so straight!
I imagine the Buzz is similar.