BB SIE, 63, & 79, what order do you take? Which is easiest? Hardest?

I'm fairly certain that you must take the SIE prior to taking the 63 and 79, as the 63 and 79 are considered top-off examinations. Regardless, of the three, the 79 is the most "difficult" (based on volume and content) followed by the SIE. The "difficult" portions of the SIE relate to random one-off topics such as annual limitations on political contributions. The 63 has material that is unfamiliar to many candidates, but the exam is quite easy to pass, as 85% of the questions source from three of the five chapters.

The order in which you should take the 63 or 79 (assuming you take the SIE first) is dependent on your other scheduling windows. Are you testing at a Prometric site? There is quite a bit of current backlog that might dictate available testing dates. For example, if the next available test date is 2-3 weeks from the day you are checking the Prometric site, you may opt to take the 63, as the material can be covered thoroughly in that time frame. Regardless, none of the material is difficult assuming you prepared for the technical components of recruiting, survived your summer stint, and attended your accounting and finance courses in college.