Obviously, Germany. If you do not know why then just do a Search of CBO to find out.
France was another country but, sadly, I've only had negativity from event people going back a long way. It just seems that as soon as you mention the UK eyes roll and the "No, we don't really want the English here" (that was actually said to me by one organiser in 2007). But why? There are many French people wholike UK comic strips -enough were reprinted in Atoll and BritComics has a lot of the covers from this and others in its photo section. I've chatted to and met French comickers and they are nice and as excited about comics as anyone else. One day maybe! I've certainly supported and promoted French comics/BD on CBO.
Netherlands and Belgium. Not been to either since the 1980s but used to know a lot of comic fans and Small Pressers there. But never here or see books from either any more -but I do go through the Dutch comic albums I have every-so-often.
Never had any real feedback from Spain -I do have a few 1980s/90s comics such as Edicione Dolares Mental Man.
Listen, if its a country with comic fans I'd go!
You can always dream. It's free!