This is kind of a controversial topic when it comes to anime, but after re-watching it from episode 1, I noticed that for one, the art is amazing, especially with the backgrounds. The characters were obviously well planned out from the start because they really felt real in my head. Also, they slowly introduced new characters and didn’t just skip out on them to move on to more important characters. I mean, Asuna didn’t get much character development in the first few episodes but came back as one of the most fully-developed characters in the entire anime. I mean, it was so good that they made a few games about it and developed the story even more with a second season and two movies! Though, some people wouldn’t agree with this, especially some people online
SAO has got a lot of hate online for making its protagonist really OP and having all of the girls in the anime love him unconditionally, but I know that he’s not OP because he’s the protagonist, he’s just the protagonist because he’s OP.