If you're talking about talent that would transcend eras then Maddux, Smoltz and Glavine should be up there as well. But if we're comparing a specific year, its pertinent to note how well that rotation did when compared to the rest of the league. And while i agree those pitchers would have been successful in the middle of the steroid era, i doubt they would have been so to the same extent.
I have a question:
Which season do you consider more "dominant":
Jim Palmer's 1975 season or Greg Maddux' 1998 season?
I ask this because they had similar seasons (albeit Palmer had a shitload more IP) but i personally consider Maddux' year to be more impressive given the environment they were pitching in.
Take their ERA+, for instance (it measures a pitcher's performance to the rest of the league) Palmer's was 169, while Maddux' was 187, and that's a reflection of generational differences.
In fact, let's use ERA+ to compare both rotations:
1998 Braves:
Maddux: 187
Glavine: 168
Smoltz: 144
Neagle: 117
Milwood: 102
1971 Orioles:
Palmer: 126
Cuellar: 116
Dobson: 109
McNally: 117
Compared to their peers, the 1998 Braves rotation was superior, and that has a lot to do with everyone hitting HR's left and right, and the inflation of run-scoring to a degree never before seen by baseball.