For me, it was my Vienna lager. I'd tried to make Oktoberfest many times but always messed up something -- usually I think it had to do with the yeast selection and fermentation control more than anything else. Finally, I made a Vienna lager with 2206, it was my first time using that particular yeast strain, and as you know, Vienna and Oktoberfest are almost identical styles (some might say that they really are one and the same). Anyway....... it was just about the finest lager I have ever made. Need to brew that one again soon. I think it really was all about the yeast. 2206. Accept no substitutes. Except maybe for W-34/70, I've made a fantastic helles with that one as well, though the beer didn't keep for long, went stale after 6 months. Again, probably my fault. I need to brew some lagers this winter. Really need to. But of course I have a long waiting list of ales I want to make, so I don't know how I can squeeze all of it in........
Also, the first time I ever made a dubbel, it was fantastic and scored a 41. I have tried making it two or three times since then, and it's never been quite the same! Still chasing that one. Next time I am going to try underpitching and see where that gets me. Again, with respect to yeast, it's definitely got to be WLP530. Accept no substitutes! That much I do know. Wyeast ain't the same, no way no how, not with my best dubbel anyway.