Prisoner Without A Name, Cell Without A Number or Compromising Positions.
I'm glad to see someone mention Compromising Positions, which if my memory of the film from 34 years ago is accurate is his best score by far -- and comedy-mystery is not an easy genre to find the right musical tone for (Addisons and Mancinis are few and far between).
No soundtrack release, of course, and not a particularly well-remembered film, but at the time it seemed surprisingly charming (especially since it was burdened with an unpromising trailer). It was also one of a handful of films shot by Barry Sonnenfeld before he became a director (and I won't mention Nine Lives if you won't).
Besides of the obvious ones (such as Terminator 1 & 2) I do love his scores to such films as:
The Accused The Baron and The Kid The Big Easy Cold Sassy Tree Hostage (TV-movie starring Annette Bening) Immediate Family Let`s Get Harry The Real McCoy The Serpent and the Rainbow Striking Distance (this really deserves to be released on CD)
but on the other side of the coin, my least favorite Fiedel scores are:
Blue Steel and Teamster Boss: The Jackie Presser Story These are in my ears his worst scores.
I can never choose between The Terminator and Terminator 2. Both are endlessly listenable and unique. I'd love if he would score the new movie (that way it would have one reason I'd want to see it), but he's not interested and I'm sure the studio would saddle him with a more "hip" composer (as is happening with Top Gun: Maverick).
I don't think anyone mentioned his score for the movie PURGATORY. I did a separate thread on this movie and score. Below is the final gunfight scene. There is a bit of music at 1:49, but the real themes kick in at about 4:50, and the end credits also use his themes. I don't believe this score was ever released. Too bad. Also, it is a good movie.