In terms of hurdles, of those four I think Danish is a clear winner there. Finnish is "ah, hell no" as far I know. :) In terms of usefulness, I'm not sure - may

In terms of hurdles, of those four I think Danish is a clear winner there. Finnish is "ah, hell no" as far I know. :) In terms of usefulness, I'm not sure - maybe Polish. (That seems quite complicated grammatically, like other Slavic languages.) Chinese, if you don't care about writing it, is simple grammatically (though a few concepts are hard to wrap your head around).