Why is nirvana the best band in the history of ever?

That's a very subjective question... I personally love Nirvana, but this is an opinion not a fact. If you must give a legitimate answer for homework or a quiz, I would say that Nirvana is an incredible band because they greatly influenced grunge as a genre. Kurt Cobain established many different guitar styles that have carried over into grunge music today. Also lyrics written by Nirvana were very emotional at times which is a good quality for music to have.