Provably Nichijou, its humor and characters can be so surreal at times yet the whole show is so mundane at the same time. But Yuru Camp can heal your soul and it’s so cozy.
Lucky Star. Konata is such an iconic character, it's pretty hard to compete with her immense otaku power. Also, the show is genuinely quite funny, and the live action endings / karaoke are so creative. It feels like everyone involved had a ton of fun making the show. It's like a big in-joke that you're invited to be part of. Ultimately, though, it's that the character designs are all just so likeable.
Azumanga Diaoh. It's kinda the OG, and really popularised the genre. There's lots of silliness, but they always commit to the bit, and it just works.
Full Metal Panic: Fumoffo. Legit one of the funniest anime I recall ever having seen. That said, it was a long time ago, so I don't remember too much else about it other than laughing a LOT.
Still K-ON!, TBH. I like band-themed anime, it's more than one season and there's just enough yuri injected to spice it up (though it's more of a running gag than anything trying to be serious).
I really enjoyed the more recent Laid-back Camp/Yuru Camp. Incredibly chill.
Nichijou. The art is real good, the structure is interesting and it has some subtle moments that make it really shine. Many refer to the crazy moments and the comedy but it's so much more in my opinion. In shared second place I have Lucky Star and Hidamari Sketch.
As a note, deciding your favorite anime or ranking anime is quite difficult. I watched Nichijou years ago. Over time I watch more anime. I rate purely based on emotions, nothing objective. How I feel about it. But comparing that across years is very tricky.