Basically the NeoPixel library came first
is simple to install and use
and Adafruit supports it
making things simple if you are a beginner
Note that even the Adafruits NeoPixel Uberguide recommends FastLED for advanced use.
Nearby I'd like to build a stairslight and I'm actually not sure which library I should use.
Many of the current "fastled" libs won't run under CREATE
would not work on Create DEV side
I had a wrod on GIT
needed to make a change to the H file.
There is a good group and forum