I entered split op my Junior year in High School and now that I am a Senior I need to consider AFROTC or AROTC. What are pros/cons of each?

It depends on what you want to do. In the end, it doesn't matter which one is cooler, laid back, more badass etc, what do you want to invest your life in?

Not really pros and cons, just considerations:
- Ironically, if you want to fly, Army. Only 5% of the AF flies. Other 95 % is handing them the saw.
- Army is all centered around people and not stuff. Mission first, people always.
- AF is centered on technology. Fly, fight, win.
- if you want to lead, Army. Lieutenants lead platoons and Captains command companies, troops, and detachments.
- what a captain commands in the Army, a LTC commands in the Air Force. This is a function of ground combat and not a negative jab at our winged brothers.
- the AF is smaller than the Army. That just means, statistically, there are less opportunities for promotion, select schools etc. 10% of 1000 is larger than 10% of 100.
- if you are naturally skinny, the AF may be for you. Their PT test factors in a waist measurement where 38" or less is studly. You think things like this don't matter until you get old and shit gets real physically.
- Army, I think, takes a wider swath of people as others mentioned. AF tends to focus on STEM. If you want to actually be in hard engineering, managing construction though, Army. Branch engineer, track your experience through NCEES to pursue a PE license. Get To USACE as a PM and District Commander. USACE has the title X responsibility for construction. If you want to do research etc, AF.
- if you want a career supporting aviation, either may get you there.
- if you are looking for full hooah now and something more cerebral later, Army. Look at the branch detail program. Example: branched Ordnance, detailed Armor. Two years as an Armor Officer, transfer to Ordnance.
- only the Army has embraced the full powers of the Warrant Officer.

As a former college ROTC cadre member, I have some questions that you should ask yourself...

1. What school do you wish to attend? (certain colleges / universities may have both or just one)
2. Do you wish to continue drilling in reserves while in school? (Army ROTC allows for dual reserve and cadet status, Air Force does not allow to my knowledge)
3. What major do you wish to pursue? (Although both Army and Air Force prefer STEM, Army may be more accommodating of liberal arts for scholarship consideration)
4. What is your PT test score? (Army requires slightly more sit-ups to pass, Air Force requires slightly more push-ups)
5. Where would you like to be stationed after graduation? (Although assignment is based on performance and service needs, there are certain places that have one service, but maybe not the other)

I can’t speak for AROTC, but here’s the typical breakdown for AFROTC. Your first two years are spent in the GMC or General Military Course. These years are focused on learning about the military as a whole and small team leadership. After your sophomore year your information goes before a board and they decide whether or not they need you as an officer when you graduate. If you are selected you complete field training the summer before your junior year. The last two years of ROTC are spent in the POC or Professional Officer Course. During these years you learn more about officership and leadership. As a POC, you help lead the cadet Wing. Typical weekly schedule varies. The basic schedule is PT twice a week, leadership lab, and a class about the Air Force. On top of this there are extra curricular activities such as Honor Guard, Arnold Air Society, and several others. As you progress through ROTC you will probably be assigned jobs within the Cadet Wing. These typically start sophomore or junior year.