Army Reserve vs. Army National Guard?

I believe the relative difficulty of overcoming the RE code will be the same for either component

Not sure if you are still monitoring this question a year after posting, but here goes...

Both the USAR and ARNG qualifications for enlistment and process for waiver submission and approval fall under AR 601-210, so the actual process is no easier or more difficult than the other, since the steps are the same. Either way you need an RE-3 waiver at the General level. For USAR it would be the CG USAREC (Commander for Army Recruiting Command), and for the ARNG it would be the State TAG for whichever state you're attempting to enlist for.

With that being said, the ARNG may be easier in some circumstances, depending on how hard up the state is to fill vacancies and if they are short on otherwise qualified prior service Soldiers. Since USAR and Active Army are both processed by USAREC, qualifying for a waiver in the USAR is typically held to the same standard as qualifying for an Active Duty waiver. It is the same company, battalion, and brigade commanders for both that have to give their recommendations before sending it to the CG. ARNG recruits separately because they are filling state specific vacancies, so a little more latitude could be expected.

For either Guard or Reserve, you would need to demonstrate that you no longer have a mental condition that potentially interferes with assignment to or performance of duty due to disorders manifesting disturbances of perception, thinking, emotional control, or behavior, in order to qualify for a waiver. Essentially, you will need to show that you have matured.