lmao @ whoever said Gurren Lagann is fanservice.
Exactly why it makes a good first anime: the intentional over the top action is the perfect hook; you can unplug your brain, because no one wants something too confusing for first anime; and when you watch another anime that has a much deeper story, you realize there are shows that are much better than Gurren Lagann.

But not only did SAO lack a good plot, but the action was sparse and not attention-grabbing. It skipped from level 1 > 20 > 60 > escape game early way before level 100; and no action/boring story in between.