The Guard has been activated stateside more in the last couple of years than in a long time. COVID, extreme weather events, January 6, BLM, and probably a couple of other things I am sure I am forgetting. Deployment cycles abroad for the Guard are generally once every 5 years, though sometimes units will get skipped over. So you’ll have a trainup for 4-5 years and then deploy somewhere (in addition to the random as-needed activations). Generally the Reserves will only deploy abroad somewhere, but their deployment cycles will be more consistent (vs. skipping years) and they may be shorter. Unless you are in a super intense Guard/Reserve unit though or you have a terrible relationship with your leadership, you can generally choose not to go because (at least currently) there are fewer slots for deployments than slots in the units matched to those deployments, so not everyone gets to go.
You can find a Guard unit or a Reserve unit nearby to where you live.
The answer below is correct about tuition—you need to be activated outside of your initial training time to get the main GI Bill that covers a lot of tuition, and you need to be activated for 3 years collectively to get the Yellow Ribbon Program which covers full tuition at an expensive private program.
Insurance is the same—Tricare Reserve Select—Humana Military / Concordia Dental. Unless you are activated, then it is Active/free insurance (Tricare Prime I believe?).
Career capital depends on what you are trying to do after/in the military. Generally though, I would say the flexibility of the Reserve probably outweighs any marginal benefits the Guard may have. But it also depends a lot on your specific unit in the Guard or Reserve and your specific commander/your commander’s commander.
Still useful to talk with a recruiter and ask specific questions, but they have their own priorities and are going to shuffle you into whatever slots they get the most points for. Looking at the websites of the military services which detail different jobs is helpful to get a baseline. But the most helpful thing will be talking to people who have done various jobs and been in various units. Your unit and the leadership are comparably important in the Guard/Reserves to the job you are doing. You can only figure that out by talking with people and finding a good unit.
There might be some new Space Force opportunities to build things out because they are so new, but there will be growing pains as well as they figure out how to actually add value without stepping on other branch’s toes. Generally your job, unit, and leadership are the most important regardless of the service, though there are various stereotypes over different services which may hold true in more situations than not (Molly gets at some of them above).