As with other threads in TravelBuzz, this list is so subjective and all airports have pros and cons that might make an airport "great" in one category but "awful" in another.

Example: I miss SEA in many aspects but not in others.
SEA has tons of direct flights between AS & DL with many routes having high frequency. Great SkyClub (and now the AmEx Lounge is nice; the AS lounges aren't bad either). Great shops at SEA (I love going to "PlaneWear"). The competition between DL and AS often meant decent fares. But other aspects of SEA outright suck. Getting to SEA from where I use to live and where I now often go for work sucks. Traffic at the airport usually sucks. Security is usually a mess. Baggage claim can be a disaster (I quite frequently got my 2500 "Bags on Time" miles from DL there). Now that I travel there and don't live there and have to deal with the Rental Car center more often, that sucks.

Now compare that to my current home airport: DAY. DAY has minimal direct flights and no lounges (not counting the small USO outside security). But I can comfortably predict traffic getting to DAY and comfortably predict other aspects of the DAY travel experience and if I pull into the parking lot at DAY 90 minutes before my flight, I'm almost certainly sitting around at the gate for 30-45 minutes before boarding after waling to the terminal, dropping off my checked bag (if I have one), and clearing security. I can also affordably park at DAY (can't usually say the same for SEA) and getting out of DAY is a breeze. So while there are some drawbacks to DAY, DAY is itself a great airport in the convenience and minimal hassle it provides.