If you're looking to get certified in first aid and need it seemingly arbitrarily for a job.  Get the basic First Aid certification.  But if you want something slightly more advanced and much more interactive to actually learn and have a little confidence in medical care - take one of the other types of first aid.  I took the Wilderness First Aid course.  A two day course where-in there was a lot of outside medical scenarios.  The best was putting  make-up on and having others figure out and handle our ailments.  My instructor Ann was one of the best instrustors you could possibly have.  Smart, experienced, funny, and interactive.  If you have the chance - take a course with her.  It's worth it isn't it.  To have at least a basic understanding of how to care for others if neccessary.