What if in 1935 when the Abwehr chief stepped down someone else got the job, say an army candidate as nearly happened before Admiral Raeder backed off on his opposition to Canaris. I can't seem to find who that candidate would have been (maybe Rudolf Bamler, OTL's head of counterintelligence until 1939, Nazi party member, and later Stasi officer), but let's say it isn't someone as opposed to Hitler as Canaris later became (he was an enthusiastic Nazi for a while until the grim realities of the regime were exposed).
Based on the chapter in the book "Myths and Legends of the Second World War" by James Hayward about Canaris it seems that there is a lot of evidence, though as yet no smoking gun due to the classification of British intelligence records, that Canaris was likely working with British intelligence during WW2 to stop Hitler. Based on a number of other articles and books I've read about him it is likely Canaris actively sabotaging the war effort and may well have been doing it in some level of coordination with the British.
So what if there was someone in charge of the Abwehr who, though not a committed Nazi was at least not interested in sabotaging his organization to defeat the regime? Canaris built the Abwehr from nearly the ground up (going from a staff of 150 to thousands before WW2 started) so what existed IOTL was his baby. Might there have been a better performance of military intelligence without someone actively working against the regime in charge?