My number one? The same one I always post, since I got rid of the rest:
Why? Because I set it up with all my favorite components (a pleasing blend of first-gen Dura-Ace, Cyclone, and Superbe) after discovering how much I loved the fit and ride when I was running it single speed. The color doesn't hurt either, being a super sexy scarlet that will never come through in pictures. It's been with me through two century rides and two minor wrecks. The gearing is set up to give me maximum options in the midrange, and while I suffer a bit on climbs and top-end speed that's an okay tradeoff. Bonus: the clack-clack of the brake levers is at just the right tone to grab the attention of roadrunners as I approach.
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A race bike in any era is a highly personal choice that at its "best" balances the requirements of fit, weight, handling, durability and cost tempered by the willingness to toss it and oneself down the pavement at considerable speed. ~Bandera