I have all the Birthday Bourbons (except the recent '06 release), and I'd rate them in the following order:
1. 2002 (Absolutely spectacular! The Grandaddy of 'em all! A hard act to follow!)
2. Spring 2003 (I love this one because it just SCREAAAAAMS dark fruit...even if you don't claim to taste all the nuances of bourbons, if you add a dash of water to this one and don't taste dark raspberries & cherries you better give it up!)
3. Fall 2003 (surprisingly a different animal than the Spring...much more woody and what I'd consider more traditional)
4. 2005 (I got a funky lilac nose and palate from this one...it was okay, but not really what I expect from OFBB...it reminded me of old-lady soap).
5. 2004 (not too bad, but definitely not in the mix with the others...you could definitely taste that it was the youngster of the bunch. I can't imagine what made this particular set of barrels stand out to the tasters!? It reminds me of the original Woodford Reserve only with a worse nose).