I think "3" is a bit underrated - of course the vampire story has been done to death but at least this episode offered a new spin on it with the "unholy trinity" and Mulder having to protect Kristen (who on an unrelated note, was pretty hot). The episode had a good ambiance overall and I liked the house it was filmed in (was this set re-used in "Sanguinarium"?).
While it's not among my "worst" episodes, I never really caught onto "The Field Where I Died." The guest acting was superb but the storyline itself and Mulder's hypnosis scene which dragged on ad nauseum just didn't do it for me.
5) "Chinga": for an episode written by Stephen King, it wasn't very frightening.
Say what you want but as when I watched this as a kid that doll freaked me the hell out! Especially the opening scene.