I happen to use this one myself though. I have found it to be relatively easy to use and one of the more affordable options available at $60 for non-commercial use. They just released 6.0.
EDIT: Removed Audacity mention as an alternative because Audacity isn't a DAW.
So many random people use Audacity because it's zero cost, and every one of those people is an opportunity to implicitly teach what's actually going.
Yes, they could all go watch Monty's excellent video showing what's going on, but they needn't do that if the tools we give them show everything properly in the first place, they'd just assume "Right I guess it's magic somehow" and only need Monty's video if they needed to actually understand (or argue with people who are wrong on the Internet).
Everything else about Audacity is pitched just right for an audience that doesn't need a full-blown DAW anyway.
ReaScript: can program high level UIs/project manipulation/etc in Lua or EEL2
JSFX: can write realtime signal processors in EEL2
Video: can write/edit video FX in EEL2 (a ton of included presets are there which can be tweaked on the fly)