It just struck me recently and I'm sharing.
As a millennial who enjoyed these shows as a young(er) adult ... I cherished them both, and at the time probably like 30 Rock more, and probably would have said that it's "the better comedy".
Over time though I've noticed I basically don't really think about 30 Rock ... frankly I almost certainly think about Seinfeld more ... but Community has "seeped in" to my TV subconscious fabric.
If I were to re-watch either right now, it'd be Community hands down. It'd be heart warming and comfortable and, I suspect, more relevant or still meaningful. By comparison, I wouldn't be surprised if 30 Rock would feel more dated, "noisy", and kinda culturally narrow and specific in a not-coincidentally SNL-like way.
30 Rock may still be "the better" TV Comedy (whatever that means). But it was written by a TV writer about making TV in New York, while Community was written about TV and its fans, IE "us", living in any random city.
I just started 30 Rock last month and am roughly halfway through Season 4—no spoilers!
Snape kills Dumbledore.
In the series finale, it turns out that Frank was made entirely of chocolate the whole time.