There is no 1 Dutch language. The Dutch, spoken in Belgium is totally different from the Dutch, spoken in The Netherlands. Even within Belgium, there's a big difference between the Dutch spoken in the different areas.
There is only one official Dutch, known as Algemeen Beschaafd Nederlands (General Civilized Dutch). Flemish, despite being spoken in another country (Belgium), is actually quite similar to Dutch; sure there are some different words an expressions, but most
Dutch people can understand Flemish and most Flemish people can understand Dutch, at least to some degree. The other true Dutch dialects, Fries and Limburgs, despite being spoken inside the Netherlands, are actually much harder to understand.
Seriously though, I recommend Spanish for the reasons given by others already. Of course, there is no one Spanish either... take for instance the Andalusian dialect.