Two of my faves have already been mentioned---Al Jackson and Duck Dunn of The MG’s, and the two drummers of The Funk Brothers (the Motown house band) plus their best-in-the-world bass playing partner, the one-and-only James Jamerson.
To those I would add Roger Hawkins (drums) and David Hood (bass) of The Swampers, aka the house band at Fame Studios in Muscle Shoals, Alabama. It is with that rhythm section and in that studio that Jerry Wexler produced those astounding recordings of Aretha Franklin, Wilson Pickett, Solomon Burke, Dusty Springfield, and many others.
And then there is the best team to have ever been in a self-contained Rock ’n’ Roll Group (self-contained meaning the members did all the writing, singing, and playing), Levon Helm (drums, harmonica, guitar, mandolin, and of course vocals), Rick Danko (bass, tuba, guitar, vocals), and Richard Manuel (piano, drums, vocals) of the God-almighty-great The Band. They are infact considered THE Band by the best musician’s in Rock ’n’ Roll.
By the way, I saw several of others' nominees live---The Who, Cream, The Jimi Hendrix Experience (as they were originally named), Led Zeppelin, others of that ilk, and sorry, those bands were not good in terms of being a rhythm section. They had their strengths and charms, but having or being a good rhythm section was not one of them. Honest!