Which is the best branch for reserve/guard duty?

Easily Air National Guard. Tons of money, lots of opportunity. the difference between guard and reserve is who runs it. Reserve is strictly federal while the guard is funded by both the state and federal government. A lot of time the reserve runs out of money very quickly and you will not be able to do much more than the minimum requirement of one weekend a month, two weekends a year. Guard generally doesn't have this problem. They get a lot more training in.

Depends on what his skills are and what he wants to do. I know the Navy reserves has programs which would allow hi. To come in at a higher due to background experience. For example, electricians, machinists, plumbers, etc., could possibly come in as an E-5, or E-6 depending on their years of experience and level he achieved in the civilian world. Best bet would be to talk to a reserve recruiter, as they would have more information for him then an active duty recruiter would.

CWO4 (Join to see)
It really depends on his background. If he has extensive experience in an in-demand career field, and advanced degree in a needed field, etc., a Reserve/Guard recruiter might be able to work with him.

Check into the Guard Gunny

I've been both Reserve and Guard. I think it depends on your friends skill sets. Consider Army Reserve is more CS/CSS, if your friend has skills which will easily cross over, Reserve might be the way to go. Reserve being federal, transferring from unit to unit is easier especially if the person lives in a border area. I also found promotion is easier in the Reserve.
Guard is more a home town unit, with lots of members from the community which has it's advantages. If the Guard in the area is more combat units, remember combat isn't an old man's game. But there must be some support around somewhere.

Have your friend contact both and weigh the advantages. There are advantages to both, it greatly depends on your friend.

If he / she is non prior service that limits the options. Have him/her go air guard.

GySgt, as many of the other responders on here will tell you this and that, it really depends on your friend. As a career Army National Guardsman, I found the Army Guard worked best for me, as I had transitioned from Regular Army to Guard. Many of my brothers and sisters transferred from Air Force Guard, Navy & Marine Reserves, to finish their careers to retire from Army Guard. Each branch has something to offer, and whichever offer works best he should follow. Also be sure that your friend chooses the branch that will work with him, his family and his employer/school.
Good Luck to him, and hopefully welcome to the Family.

I would tell anyone in that situation to get in great shape and enlist in the army or marines active duty for infantry for three years. Get the full experience including gi bills- go all in. To generalize- about a year training, about a year deployed and about a year realizing that you've done your part, you're turning forty and it's time to move on. The military will be a good adventure for a 37 year old but by 40, you've seen behind the curtain and should be satisfied and ready to get out of the next generation's way.

Unless I'm mistaken, you only have two choices the Navy or the Air Force. (Due to age. I joined the NAVY Reserve at 38. It can be done.

It entirely depends on what you want to get out of it. Guardsmen, depending on their state could have a vastly different experience even in the same branch. For example, the Washington, Oregon, and California guard are activated semi-frequently to combat wildfires in the summers.

For me, I knew the Air Force was my gig from an early age. My father and maternal step-grandfather were both Airmen, and I could not think of joining any other branch.

If your friend wants to prove he is though, and put more on the line, then Army and Marines are the better option. If he wants a slightly easier time, then the Navy and Air Force are where he should go.