Well, I've never met anyone who said that English pronunciation is "very difficult to learn". I mean, there are tons of English accents in the world anyway so it's fine if someone speaks it with an accent, in my opinion. Of course, if someone wants to be mistaken for a native speaker, it will be difficult to perfect their pronunciation to such a degree, but it would be so with any language because sounding like a native speaker is difficult no matter what language you are learning.

To anyone who still thinks that English pronunciation is difficult, try learning Chinese with its tones :)

If I had to change our global language from English to another, I'd change it to Spanish. It sounds beautiful, and it's easy to understand. If you speak a language with Latin roots (I realize not everyone does), then you can probably guess many Spanish words at a glance. 

I would take the Cyrillic alphabet though, because looks beautiful to me, especially in cursive.