Have a play around in South America, the gap between Brazil and Argentina to the rest is massive, Colombia are also well above the others in terms of wages etc. Continental comps are always stacked with Brazilian sides as well. Foreign player rules aren't particularly great either really, but it's good fun.
I'd say if you haven't done it before, start one in Chile as it's a straight forward league, no opening or closing stage and no average points etc.
Never done the US, as I can't be bothered to figure out the transfer/draft system