[@Asura]
When it comes to a demographic breakdown, it goes something like this:

[u]Lonthin Empire[/u] has the lowest level of diversity, and the least exotic races. Humans, Elves, Halfings, Gnomes, Dwarves. Common is, of course, the most dominant language, and Elvish comes after that, but other frequently-used languages come from the aforementioned races(Gnomish, Dwarvish, Halfling, etc). There [i]are[/i] other races as well, but they are [i]generally[/i] treated as second-class citizens - at least unofficially.

[u]Xernoa[/u] probably has the second-least diverse population, but is still [i]much[/i] more tolerant than Lonthin. The most common peoples here are Humans, Leonin, Loxodon, and Aarokocra - though there are, naturally, others scattered about in significant numbers. Most common languages are Common and Leonin, and then Loxodon and Auran, then others.

[u]Allyanik[/u] is a rather diverse territory. Due to the cold northern areas and warm southern areas, it can be comfortable for a wide array of people. The most common people are Humans, Tabaxi, and Hadozees, but not by a strong margin.

[u]Scithia[/u] is a dice-bag, of sorts. You generally don't really want to go there if you have the choice, but speaking Common will probably suffice if you do. People group with who they have to to survive, so some areas are language-diverse and others are not - it's pretty difficult to measure. It is, however, notable that races who like wet environments are likely to be drawn by the constant rainfall. Notably, this area has the highest populations of Giff - but they predominantly speak Common. The more society-inclined Lizardolk have lived here for a while as well.

Finally, the [u]Tembloran Coalition[/u]. It holds the most exotic races and is pretty diverse. Orc-kin, Goblinoids, and the rougher folk are quite common here - speaking Orc, Goblin, or Draconic could prove useful. There also exists Humans and Grung, even if in small enclaves. There is some spill-over from the Eastern continent-island as well, which is chock-full of Feykind. Firbolgs, Centaurs, Satyr, Elves, etc. densely populate that area - so Elvish and Sylvan are quite useful.