For me, the highlights from Rattle's Mahler cycle are his M3 (very underrated); the scherzo to M6 (placed third); M8/2 (Part 1 rushes too much near the end, but Part 2 is excellent), and the transition from the fourth movement (second scherzo) into the fifth movement, on his Berlin remake of M10.
Many people feel that Rattle's earlier Bournemouth recording of M10 is better, but I don't. On his remake, he tones down the solo bass drum shots that were just ridiculously loud on his first recording. Even better, he makes a huge slow-down at the final expressionistic outburst towards the end of the second scherzo, and keeps with that slow tempo all the way to the start of the fifth movement: the first solo bass drum stroke. This works perfectly, as it makes for a natural transition. The problem with his Berlin remake is simply that the sound isn't all that good.
