Could be fun to consider… what do you mean by ‘world’s best computer’ ?
Which measures of computer goodness would you want to hyperbolize the most ?
Top class supercomputer can accurately model flight performance of a new aircraft before any part of it is built. And it could model weather patterns But it might not be worth the trouble to get it to play YouTube or to do anything for a week on one battery charge.
The CGI server farms at a place like Industrial Light and Magic or Disney can generate thousands of 4K resolution frames of a new movie a day, behaving in a real sense as one super-multi-tasking machine.
petaflop is the sort of unit of computing performance of those rigs.