One piece

I don't deny it being a good anime but why would people call it the best anime?

everyone has their favorites and thats ok

By far the most expansive and well built world, simply by having so many episodes

its 100000% not the best, its good but because of how unbelievably long it is there's bound to be strong lows of the story to match with its highs.

I started to watch recently
stopped at ep 131 to take a break

imo it's a decent anime, but the fights are really bad and not interesting at all... Luffy is always using the same techniques, and the last arc i watched Nami used a weapon built by Usopp to defeat an enemy and it was pretty silly...Usopp is just useless at everything, but a good character, Sanji is always kicking things, boring... and Zoro is the most interesting one
btw the characters' personalities are the best part of the anime.

It's just okay, nothing insane. I think Naruto is better.

Bcoz it's just that good

i physically cannot believe there is a person out there who was sat through all 1100 episodes of a 30 year old show

Longetivity and well-built world and story with dots connecting as the chapters go by. Well thats my reason.

"I don't deny it being a good anime but why would people call it the best anime?"

Why do you question other people's preferences? That's dumb