It depends on how you want to define the top players. If you're looking at integral to the team, then it would be:
1. Hampton - Played DE and DT, collapsed pockets, broke up blocking schemes, and caused general havoc that let him and others make highlight reel plays.
2. Singletary - QB of the defense, read plays, lined people up, and did his job own well.
3. Dent - Provided consistent QB pressure to allow DBs to make plays.
4. Marshall - Playmaker, period. He could do it all: cover, sack, tackle, and create turnovers.
5. Duerson - Played the 46 position that made running on the team impossible.
In terms of pure talent...
1. Marshall - Incredible range and recovery speed. Excellent tackling, sticky coverage, pass rush ability, and excellent instincts. Always around the ball. I believe that if he stayed with the Bears in the scheme he thrived in, he'd be up for HOF consideration.
2. Dent - Amazing footwork for man his size. Raw coming out of college, but with his speed and reach, he made it look too easy at times. Even though people rip on his run D, I remember a play he had against the Rams where he launched himself like a missle over a guy trying to go low on him and nail Cleveland Gary in the backfield.
3. Hampton - Versatility, great moves, strength to collapse pockets, excellent hands, and a smart player to boot.
4. Frazier - For a while, one of the best cover corners out there. But, I didn't consider him integral because the pass rush that year was so excellent, the CBs rarely ever had to cover anyone for long.
5. Singletary - Great instincts and ability to read plays. Solid tackler, above average range and ability to be in the right place.