AIFP. Not that the other two aren't valuable, but ETOPS is a relatively simple concept (though saying you've been through an ETOPS course if you apply for a larger airline that may utilize it after your first job would be helpful, I would try to do both AIFP and ETOPS if doable) and it's unlikely that an EWINS workshop would impress a hiring manager, only if you have full EWINS certification would that be an asset, and the vast majority of dispatchers don't possess or require it.
AIFP really is an eye-opener as to the complexities and career possibilities of international flight. When you get a job someday at an international carrier, the information contained in the binder can be an excellent refresher to prepare you for what's ahead. For example, though my present company still hires folks without international experience for our international operation if they are otherwise well-qualified, I believe I had an edge over other applicants for that one open position in part due to a) an understanding that I knew what I was getting into, b) demonstrating that it was a genuine career interest shortly after completing my dispatcher certification and c) well, the company was impressed enough with the course material to suggest that they would consider giving a candidate a conditional job offer to those who had completed the course in lieu of actual international experience. When it's time to take that next job, you can always head back for free lifetime refresher training on the subject.
