Oasis declaring themselves the best band in the word was just ridiculous. I'd like to think it was said tongue in cheek but it probably wasn't.
of course it wasn't tongue-in-cheek but if you cast (no pun intended) your mind back to that time, remember what the response from ordinary decent music fans was. The Spice Girls were huge then too and it was put to Oasis that, rather than them being the biggest band in the world, it was actually the Spice Girls. They had more hits, sold more records, and everyone could name every member of the band, unlike Oasis (who I still wouldn't know beyond the shitbag twins and bonehead)