Thinking about transitioning from AD to NG/USAR. Which one is better, in terms of officer progression?

in the Guard there is a certain amount of Politics involved and especially the higher up you go...

The Guard is 54 different animals. The generalities here aren't applicable to all places. I see your a Captain so if you drop yourself into the D.C. Guard you'll have a heck of time on promotions. (They have a battalion and some other overhead. If you drop yourself into the Pennsylvania/Texas/California /Alabama Guard there is a lot more force structure. The Guard is short on Majors (in general) as is the USAR (See AC to RC Bonuses for both Guard and Reserve to attract individuals like you; both are offering -I think- up to $10,000 right now depending on your skill set).

I have been in both the National Guard and the Reserves. I will have to disagree with some of the comments about the Guard as I found that the Guard is concerned with professionalism as much as the Active Army is because they have had that stigma of being a family affair for so long. I was an ROTC graduate from college commissioned into an Engineer Battalion in Georgia. I served for 18 years in multiple assignments within the state and several construction missions overseas. I was selected for schools when it was appropriate and when I applied for education. I transferred to the Reserves and was promoted to O5. As for travel I traveled to most of my assignments in both the National Guard and the Reserves - I live in Augusta, Georgia and have drilled in Atlanta with the Guard and Charlotte, North Carolina while in the Reserves. I hope this helps.