Destined:

Things may have changed since I served in the USAF in the late 80's and 90's but I doubt it.  So here goes.

First, you're starting with some faulty premise that you can join the USAF, obtain a particular MOS, and based upon that be selected for flight training. This rarely happens.  If you want flight school, talk to a recruiter and get a guarenteed flight training spot in writing  before you sign on the bottom line. 

Second, even if you get a pilot slot there is no "you're going to be a fighter pilot" guarentee.  Two thirds of most flight training classes transition to heavies or as we used to call it, CATT(Civillian Airline Transition Training).   Selection for fighter training is based upon performance.  

Let's assume you manage to get into flight training. There are stated criterion for selection to FLIT (Fighter Lead In Training) and unstated ones.

Some Stated:   Speed that you learn, "situational awareness", leadership, military bearing, etc.

Unstated: You like to party but don't get out of control, you would fit into a college faternity (this applies to women also), athletic looking, "smarter than the average bear", you're someone the deciders wouldn't mind having a beer with, you're a risk taker. Read Tom Wolfe's book, "The Right Stuff" (watching the movie doesn't count).   While things are now more politically correct, things haven't changed all that much.

Still want to take your chances?   Assuming you can pass all the unstated requirements, GET A CIVILLIAN LICENSE TO INCLUDE AN INSTRUMENT TICKET AND ALL THE HOURS YOU CAN AFFORD BEFORE JOINING.

If you really want to tip the odds in your favor, get Acrobatic training and see if you can talk your instructor into teaching you basic formation flying with another instructor as "lead".

Finally, which service do you want to go in?  Let me give you my highly biased  opinion.

Compared to the USAF, the Navy has gotten some great press (think "Top Gun",  "An Officer and a Gentleman", etc.) not to mention their insistance on being called "aviators" and their little ditty, "I don't know but I've been told, Navy wings are made of gold.  I don't know but its been said, Air Force Wings are made of Lead".  Here's the reality.

Navy:  You spend 6 months of the year on a Carrier in the middle of some ocean. Your "quarters" are basically a metal closet.  There is no booze, you're surrounded for the most part by other men (and you can't date the few women on board), and you fly over a featureless ocean.  There are strict divisions between the ranks, and a lot of spit and polish bullshit.

Marines:   Same as the Navy but even more spit and polish bullshit, white wall hair cuts, and you only get aircraft and equipment the Navy doesn't want.

USAF:  Except when deployed, you live somewhere for three years.   You fly mostly over land (someday, ask me about flying low level in Alaska) which is awesome.  You live in a house or apartment.  At the end of the day, you go off base for some action, or to the Fighter Bar at the O club, and more often than not, hook up.  Since in the USAF only the officers do the fighting, the enlisted ranks tend to be intelligent, and self motivated.   In the air, the most qualified pilot is in charge of the formation.  For example, during one assignment and as a Captain and IP, I often flew as Flight Lead with the Vice Wing Commander --a bull Colonel--as my "student" and wingman (yes, he had tons more experience than I did and was one hell of a stick, but his "additional duties" of helping run the wing meant he had to fly with an IP).    The result of all this are that the Officer/Officer and Officer/Enlisted relationships are more relaxed.

There is a minimum of spit and polish bull ***.

Hope this helps.

"Flash"