I recommend Reflexite REF-DB Retroreflective V92 Daybright Tape,
found on Amazon. I use it on my commuter. It is very bright! It comes in several different colors. I ordered the silver/white and red. Be sure you know exactly where you want to lay it because it is difficult to remove. The tape has been on my commuter/winter bike for two years, and at this point the fraying tape needs to be removed and replaced.