With the SUPT track, after initial training in the T37 you select (or are selected for) either fighter track or the heavy track.
If you really want to fly fighters, or your heart is set on heavies, you can probably have some chance of getting what you want. If you walk in going "I want a C17 to Charleston" or I want an F15 at Langley, you may not be so lucky.
My advice is to go with the goal of A) Getting Wings , then B) getting Fighters or Heavies (your choice) and only then hoping for the perfect plane/base match. Since your UPT committment is anywhere from 8-10 years these days, you will likely have 3 3-year flying assignments. If you don't get the base of choice on the first try, you may very well get it later on in your career.
I flew OV10s at Shaw for 2 years, then transitioned to the F15. I've had buddies go from A10s to the F15. I have three upgrading IPs in my squadron right now that flew heavies for a while (back when UPT was single track...ie everyone flew the T38) and when they graduated there were no fighters available. A few years later, when the AF needed more fighter guys, these guys made the transition. You may have seen a post on a UPT buddy of mine (Reuterf16) who flew F15s, F16s, and the U-2.
Bottom line--go to become a military aviator, and be flexible. Keep your eye on your long term dream plane/mission, and perhaps you can get there even if you don't go straight there out of UPT.
I kicked around the fighter verses heavy question in UPT, and I think at the time I would have been happy with either. My buddies who went to the 141, especially at Chareleston, had a great time and a great quality of life. Fighters are not a "mellow" community, and it took a lot of work for several years before I could actually savor the experience verses just working like a dog to hang on. However--all the effort has been well worth it, and I've had experiences that I could never get anywhere else.
Good luck--and I hope you seriously consider giving it a shot!
Fly safe,
Albie