My favorite words to say in various languages:  Esperanto:  insekoj, Portuguese:  liquidificador, German:  Flammenwerfer.  I'm not sure I have a favorite Spanish or English word.  Maybe the longest one for English:  antidisestablishmentarianism.  I'll have to think about Spanish.
@hobbsc  the German for 5 amuses me as it sounds like a bag of flour hitting the floor. 
@luke i will never say 5 the same again...