Which one should I join: Army Reserves or National Guard?

You do not have to do active first. It sounds like you have a good plan to get started on your education and serve simultaneously. The thing is, you really need to talk to both an Army Reserve and a National Guard recruiter. I know you're avoiding confrontation, but enlistment options and MOS selection is going to be based on what types of units are around you, or are around the place where you are going to college. There may be no veterinary units within a distance you are willing to commute, so that might not be an option. Odds are the Guard will have a little more variety for you because it is about twice the size of the Reserves. Also, if you are planning on going to a state school, many states offer their Guard soldiers 100% tuition istance or exemption at state schools, whereas the Reserves can only offer you $4500 a year. There are two ways to do basic/ait. One is College First, if you are elligible. You would go to Basic and AIT back to back (likely delaying your first semester of college) but then you would get two years of non-deployability and some extra money with your GI Bil. The other option is split option where you would go to basic one summer and then AIT the next. YOu would get no guaranteed non-deployability, but you would be non-deployable until you complete AIT the next year. You would also get a little less extra GI Bill money each month than college first kids get. Bottom line is though, you'll have to talk to both recruiters to see what they and the state can offer and what MOS selection and commuting distance works best for you. Good luck.