"I'm curious of what anyone thinks of Gielen's 1st and 10th"
Well, you certainly won't go wrong with either. I feel that Norrington is more interesting with his M1. I get tired of hearing the same Mahler first - over and over - with the scherzo being too fast, and the funeral procession that begins the slow movement, being too slow. Like Jarivi, Norrington addresses that issue by slowing down the scherzo - just a tad - and speeding up the funeral procession. Gielen has the stronger finale.
For M10/Cooke, I prefer the Ormandy. Gielen is excellent with the more "Vienna 2nd school" elements; so, his fourth movement (second scherzo) is outstanding, as is the development section of the fifth movement. But I feel that Ormandy is far better with the first scherzo; "Purgatorio" (third movement); and, the back half of the fifth movement, where the Philadelphia string section does its special mojo, and Ormandy is simply faster. For me, the Ormandy simply flows better from start to finish. In addition, Gielen's solo bass drum strokes that begin the fifth movement - as with so many of them - are simply too loud in relation to all the soft, dark music that goes on around those strokes. To me, Ormandy and Chailly get the volume and timbre of those strokes just right. I prefer Ormandy, but you won't go wrong with the Gielen; unless, like me, you feel that the back half of the fifth movement should have some blood in its veins; much less prove that it can get some kind of musical hard-on ((partly a problem with Cooke's thread-bare orchestration and undercooked (no pun intended) dynamic markings)).