There have been lots of recommendations for good daily drinkers in the $20-30 range, such as Maker's Mark, Bulleit, Eagle Rare, etc. And while all those are quite good (Maker's Mark is a particular favorite), the OP asked for the best bourbon under $50. In the $40-50 range there are some that are simply better than anything you can get for less.
Angel's Envy - The best bourbon I've had for anything near $50.
Jefferson Reserve - A real treat and the regular Jefferson's small batch is quite good also.
Four Roses Single Barrel - I keep finding that my bottle of this is almost empty, which must mean I'm picking it regularly.
