I have an antipathy to Barenboim's conducting, and I didn't care for his M7 at all. One of his farewell concerts here in Chicago was M9, and it was a disaster. First movement was WAY too fast, and the whole symphony was grey sonic sludge. It's one of very few concerts I would have left if I could have. When he left, Barenboim said he would never conduct the CSO again, and I thought, OK, it's safe to go downtown now.
Orchestra Hall is always troublesome. Haitink, whether you like him or not (I usually do), "scales" the sound of the CSO to the hall, and it sounds much more musical than with some other conductors.
I was very impressed with Jansons/BRSO in M7. It's a strong performance, and for a live concert, the precision of execution is incredible. Fine recording, too.
As for Boulez, I find his Mahler variable, but in my most recent M1 survey, his CSO recording struck me as one of the better ones. And, I will never forget a live broadcast (perhaps mid-1970s) of the complete Miraculous Mandarin with the Cleveland Orchestra at Blossom. Just a blistering performance, and much better than either of his commerial recordings (NY and CSO),. although those are both good in their way. Finally, his La Mer, Jeux and Nocturnes from Cleveland (recorded 1991 and '93) are magnificent.