I’d go with a few teams here. In the Eastern conference playoffs, my pick is the 1992 Knicks and 1998 Pacers. Both of these teams were the only teams to take Jordan’s championship Bulls to 7 games.
1992 New York Knicks
This was a tough team for Jordan’s Bulls to beat. The 1992 series vs Knicks went a full 7 games. The Knicks roster consisted of all time center Patrick Ewing, not one, not two but three big enforcer type dudes in Xavier McDaniel, Charles Oakley and Anthony Mason, one of the most consistent passers ever in Mark Jackson and two of the best guard defenders of their era in John Starks and Gerald Wilkins. This was a tough series for the Bulls because the Bulls didn’t have as much size as the Knicks, Horace Grant was a great defender and ok scorer, but Oakley had more toughness. Bill Cartwright obviously is a mismatch against Ewing. Gerald Wilkins guarded Jordan better than anyone I’ve seen. McDaniel gave Pippen quite a few headaches. and Pat Riley ofc was an all time great coach to rival Phil Jackson.
The 1998 Pacers were also quite formidable. Reggie Miller, like Jordan, raised his game in the playoffs. Mark Jackson was also on this team as well. Rik Smits was one of the best non HoF centers in the 1990s. And the Davis brothers were quite solid as well. There was also a developing Jalen Rose and HoFer Chris Mullin coming off the bench. This team was tough for the Bulls because the 1998 Bulls were probably the weakest championship Bulls team. Jordan was 34 and had a dislocated shooting finger which threw him off that season. Pippen was injury prone that season and wasn’t even an all-star. Rodman’s mentality was very on and off and was not the same Rodman as in 96 anymore. They also lost a lot of big men like Bison Dele and Jason Caffrey. That’s why this Pacers team really took Jordan’s Bulls to the brink.