The antenna is linear polarized so to get the best range it should be aligned with the antenna on your drone. However since hte drone is always moving it is not always centered so most pilots will have the antenna vertically upwards if the antenna is mostly upwards on your quadcopter.
To learn more about antennas you can check out the FPV antenna guide, as some of the principles are the same no matter what antenna. But the main reason why we dont use circular polarized antennas for R/C controllers is that CP 2.4Ghz antennas are mostly large and bulky.