All three season of SAO were really good IMO. Gintama has been around a while, but I'm not sure it's been 15 years...
If you like sci-fi Mochi, then I can recommend a great deal...it's a big genre.
Anyway, if you like the "stuck in a game" theme (like SAO), you should definitely check out Log Horizion! It's a another good one, for sure! ^_^ They take different roads than SAO did. I also really like the .hack series, which is along the same lines, but different in its own approaches from the other two.
...and if attack on Titan interests you and isn't too gory for you, then there a plenty more I can recommend! Such as Btoom...