French vs. Spanish vs. Russian?

I have a choice between these three as an introductory course, where I would begin to learn the basics of the language and grammar. My native language is English, and I am not bilingual. I did have to take french cles in elementary so know some of the basic words there, but forget most of the grammar. The only thing about french is since I am at university in canada, they do expect you to have had some previous knowledge of french from public school, so they may expect a higher level of competency (such as a gr.9 level, where what I can recall of it is probably more of a grade 6 level). French may be useful because of living in Canada, but since I am not living in that area it is not a huge deal. Spanish I know is a widely spoken language, but again, I don't know how much I will truly encounter it. I plan to be a teacher in a small town in Canada, so I will not really be in a business environment contacting too many partners across sea. I have always been very interested in the former yugoslavian culture and language (serbia and croatia namely), and I was wondering if there was many similarities between russian and croatian as well. So basically if you have any experience with the languages especially learning them as an adult that would be very welcome. I will not be bilingual with the amount of courses I am taking in the language, but if I am interested I may pursue the language further afterwards. To summarize, which of the three has the most difficult grammar to learn, is most difficult to pronounce, and from the sounds of it which do you think would be most or least suitable. I've never been amazing at languages, but I will put work into what I do. But it does not come naturally to me, and I can still never roll my r's. :( But yes any advice/help would be extensively appreciated!!