Most investors don't think of this airliner manufacturer as a sin stock, but the fact is that BA earns approximately 40% of its revenues as a defense contractor. It's that mix between commercial aircraft and critical defense projects that makes Boeing a best-in-breed sin stock for this year.Boeing's recent gains have been driven by its commercial aviation business, propelled by new offerings such as the 787 Dreamliner and re-engined 737 that are too hard an opportunity to pass up for fuel-conscious airlines. Intermediate-term tailwinds in the airline industry should be an important driver for Boeing in the next couple years, especially as it continues to unveil its next-gen airliners. Boeing's flagship defebse projects include the replacement of the Air Force's KC-46A refueling tanker fleet, a deal that could be worth $75 billion by itself. The firm has also been retrofitting old F-16s into unmanned aerial targets for military pilots to take aim at. (Yes, it's basically getting paid to help blow up a rival defense contractor's fighter jet.) With a backlog of $441 billion, Boeing has approximately five years of sales in the pipeline. That's a number that should give investors a lot of comfort over this stock's ability to earn big revenues for years to come.