I would say it really depends on your reason for learning the language: personal enrichment, you think Romanian chicks are hot or because of your career (i.e. economic gains). For the first two reasons, I cant make any recommendations (although Romanian girls are hot).
If you would like to learn a language to advance your career/possibilities the obvious choices for modern European languages are German, French and Spanish.
German is very advantageous in engineering (especially mechanical, chemical) and science. German is the most spoken language in Europe. It is not the easiest language to learn but since you seem to be Afrikaans (?) it should be a bit easier than (say) French.
French is still the Diplomat's language. The fact that they hate talking English makes it rather important to learn the language if you plan to regularly interact with French companies/colleagues. I personally find French to be a bit overrated....and it is quite difficult to learn.
I think Spanish isn't always given the status it deserves; the whole of South America except Brazil speak Spanish (oh and Spain of course). This creates (theoretically) many opportunities to apply the language. Of the three, I think Spanish is the easiest to pick up.
I wouldn't ignore the fact that you can speak Afrikaans. Although, contrary to popular belief, you can't simply walk into Amsterdam and talk away without any "eksuus!?" you'll obviously adapt very quickly (few weeks). Flemish (spoken in the Nothern regions of Belgium sounds much more like Afrikaans than Dutch (go look for some news report on the net - you'll be amazed).
To help you in your decision, consider the number of people talking the language, the geographic regions where the language is spoken ans also the associated culture of the language/country. There is no use in spending lots of time, money and effort in learning German if their punctuality and organisation fetish simply pisses you off.
You get some CDs to get a basic idea of the languages. Michelle Thomas' CDs work quite well (if you can find them somewhere ;-) )
Official institutes are very expensive but at least all certifications are internationally recognised:
German: Goethe Institut; French: Alliance Francais