By the number of speakers, some form of Chinese would probably win hands down. In any case, Hindi and Spanish (the latter with arguably much more regular grammar and spelling) would still take over English.
There's more to what makes a great language than regular grammar and spelling but, that aside, English is already gradually being adopted as the world language. The OP is complaining about parochialism slowing the spread. Whether you agree English is best or not, you might still agree that worse-is-better move to some common language improves things overall