There was a census document some japanese guy put together in a thread about which world has the largest population, can probably find it if you search the general forum. This is of course not too fresh, but in my experience, if one server contains a lot of german people for example, the german population will grow over time when more people become aware and join in. Anyway, the largest non-legacy EU servers that had the highest % english speakers were Phoenix, Odin and Cerberus (combined french and german population of about 10k for Odin and Cerberus, out of roughly 40k total for both worlds). Moogle had a fairly large french population (13k out of 31k in that census) and Shiva had a relatively large german population (don't remember any figures). Disclaimer: This is all from what I remember reading it a few weeks ago.