You're not guaranteed to fly 'fighters' in any branch...you're placed or given the choice based on how you do in flight school...the first checkpoint I believe is the break between planes and helos...if you choose planes you'll have to score very well to rate a seat in a Harrier or F-18...otherwise you go Prowlers...or you'll be a transport (C-130) pilot.
I'm a lowly NFO candidate, lol, so I've got only two choices Prowlers or F-18's. Someone out there will know more about the actual split/path to flying jets.
If you have poor study habits and/or lack of motivation you probably will never fly a 'fighter', much less any military aircraft...
In the Marines you will have to 1) Be in better shape to qualify than any other branch 2) get accepted to and go through Marine OCS (toughest of any branch) and 3) go to (before flight school) The Basic School (TBS), which is a 6 month infantry leaders course all Marine officers go through...This is no picnic...if you wanna fly ONLY go to the Navy or Airfarce where you won't have to worry about crawling in the mud after OCS...If you wanna have the respect of all of the armed forces and know how to call in artillery, lead a platoon/company of Marines in a ground assault, and ultimately want to be a true warrior, but want to fly ALSO, give your Marine OSO a call.
Military pay (base and subsistence/food money) is the same for each branch...i.e. rank and time in service rate your pay...pilots/air crews receive $150 flight pay for over a certain number of hours in the air per month. You'll also get basic allowance for housing (BAH) depending on where you are stationed and if you are married/have dependents.
I have one bit of advice for you...if you want to serve your country join the military...if you want to fly jets go through the private sector, because the only guarantee in the miltary is that there are no guarantees.
Good luck.