Walter is my #1, in fact he’s one of my all-time favorite conductors. His interpretations are able to put me in a zen-like state, fully absorbing me in the music. Performances can be very emotional. I read that he would sometimes cry after a performance, the music must have brought his emotions to the surface.
I absolutely love Furtwängler’s Bruckner. This was my introduction to this maestro and I continued to explore his interpretations of other composers. He’s criticized for his changes in tempi which purists say were not the composers’ intent, but for me, this is what separates him from other conductors. My appreciation of Furtwängler began by listening to his late Beethoven stereo recordings. After Music & Arts remastered his early works, I realised these performances (recorded in mono) were superior. I have the three symphonies composed by Furtwängler, all modern day recordings. I took to Symphony #2 pretty quickly, I’m still working my way through the others.
It took me awhile to appreciate Toscanini due to the intensity and drive he applied to his symphonies. I was put off initially by his interpretation of Beethoven, preferring Walter and early Karajan’s style. But now I become transfixed by his mastery of the composition and that of his orchestra. His Beethoven and Brahms have a brilliant Germanic style.
BTW, Klemperer should be included in your list.