Yo!
Well, I use both...here's my run-down...
Audacity is "light", but easy to use. Fire it up, hit record, just record the track, rewind, hit record again and record the next track. Audacity understands what you want to do: record stuff...
Ardour does the same. However, it involves some prepping from your part. For one, you have to ADD the new track, tweak it in the mixer and then, you can record. Ardour does seem to allow you to use external (third party) filters/effects. Audacity only allows you to use what's in there....but Audacity has the ability to program plugins yourself...in Nyquist.
As a bottom line, Audacity allows for a quick record-and-mixdown, Ardour is somewhat more extended.
The choice is defined by what you want to do...
Happy recording!!
And, welcome to the forum
Thor