I have 4 passports, Hong Kong, Australia, USA and Sweden, I used to have a British Passport as well on the account of being a Hong Kong resident. I can probably still get it if I register as a British Citizen.
I think the world best passport is BS. You never going to travel all around the world to begin with. And each passport have some destination you want thats visa free, and always some you need visa for, for example, I would use my US passport to go to Canada where you dont need a visa just register on the border post, I will use my Aussie passport if I want to go to New Zealand because of trans Tasman agreement which give Australian permanent residence in NZ. And I will simply use my HKID card if I want to go to China, no visa Hassel free, and I use my Swedish Passport if I want to go anywhere within the EU.