I've done a lot of races in my time.
In fact, I don't even know the exact count. I have kept almost all of my race bibs (minus a few strays from the early years before I considered myself a "real" runner, that is), but please don't ask me to count them.
I have had some great races, and I have definitely had some nasty ones.
If I were to name my best race experience, though, it would be tough. There are too many factors (the weather, the terrain, the crowds, the training that got me there, etc.) to name the absolute best one that I've experienced. The 2013 Quad Cities Marathon, though, would definitely be a contender.