The forum has all kinds of threads, but I don't think that there is as yet a thread dedicated to members' favourite players in accompanist roles.
Not just musicians who do a solid job of playing the chords in the background, but musicians who, by mere dint of being there, can tie an entire group together, and really sell the leader in his or her role, without stealing the limelight or necessarily even taking a solo.
My own choice for this category would not cause me a moment's thought: John Hicks. He is on all manner of records as a sideman during his height, from very straight ahead neo bop to Chico Freeman and Pharaoh Sanders. It's no accident that the records that those last two cut with him are (in my opinion) their best (in Chico's case) or a complete revival in quality (in Sanders').