Depends what you're looking for. What bike, ridden in what conditions, what weather, how much?
Just a few replies on here so far, and people are already recommending products by Finish Line or Muck Off, which are one of the worst on the market - both in terms of power losses as well as drivetrain longevity.
There are some good classic drip lube options out there - Silca Synergetic, Rex Black Diamond are one of the best that come to mind.
If you want to go a step higher you can look at wax drips - Silca Super Secret, Ceramic Speed UFO, Tru Tension Tungsten, etc.
The ultimate solution is, of course, full immersive wax. Best wear protection, best efficiency, least messy. But people are generally not that enthusiastic about it - mostly due to misconceptions.