I like using this USB serial adapter, because it has a micro USB connector, for which cables are much more common than the USB A-A cables you need to connect most other common USB serial adapters.
I find distinct serial numbers important to distinguish between multiple adapters. The CP2102 chips on the adapter come with only a default serial number, but you can easily change their serial number using the cp210x-program utility.
Available on Aliexpress for around $1.