Basil Hayden is a delightful bourbon. Booker is bottled too early, IMHO, which contributes to its harshness. You'd see a little loss in proof if they waited another 5 years, but it'd be much better.
In comparison, Buffalo Trace made a small batch called George T. Stagg (15 y/o), which was 120 proof, but as smooth as Basil Hayden. I had the pleasure of a bottle of this and I have to say it was the most delicious spirit I ever drank, and I used to live with a whiskey merchant! It saddens me I'll be paying through the nose to acquire another bottle of this since it hasn't been available for many years now.
Now being a fan of Buffalo Trace, I have moved on to their Eagle Rare bourbons. If you can find it, get the 18 y/o. It is quite comparable to Basil Hayden, but with even more intense vanilla flavors. Very smooth and delicious. Not easy to find (as opposed to the 12 y/o, which is available most everywhere that sells good whiskey) and not easy on the wallet.
[edited to add] - the particular bottling of the George T. Stagg was aged an additional 3 years (to 18) and bottled special for the shop my roommate worked at in NYC. I'd give anything for another bottle of that particular batch.