SAO was pretty terrible, but there are plenty of worse things out there. Probably the worst thing I've ever seen was Chaos Dragon: Sekiryuu Seneki. I watched it as it aired during the Summer 2015 season. It was torturous to watch.
Edit: those of you who actually enjoy SAO need to watch something good. Yes, the first half of the first season wasn't all that bad, but everything after is complete trash.
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First of all I'd like to stick up for SAO as I though it was a fantastic romance with good action and nice suspense. Also to answer your question the worst show I saw was Freezing it was just awful.