Now's a great time to buy a OnePlus One. Not only is the device easier to get, but owners have two excellent ROMs (based on Android Lollipop) to choose from: Cyanogen OS 12 and OxygenOS.
This video will take you on an in-depth exploration of what the two different ROMs have to offer. They're mostly the same, but they differ in a few key ways. Check the video out to get a thorough look at Cyanogen OS 12 and OxygenOS side-by-side, and tell us which one you decided to go with.