I’m pretty much a period instrument purist 80% of the time and hence most of my favourite recordings would be from the historically informed performance. So John Eliot Gardiner is my favourite conductor and would use his recordings as 1st preference. His Eroica performance can’t be top.

I often consult this database to listen to any work for the first time https://www.wissensdrang.com/picds1.htm

A lot of the celebrated recordings from early on in the recording history of classical music I often overlook for that reason due to them trying to romanticise/modernise the work and the vibrato.

Although out of the all the classic conductors prior to the HIP/period instrument era I do like George Szell Beethoven cycle who had a reputation of sticking to the written score and tempo and would gravitate to his conducting if there isn’t a HIP/period instrument recording of the work.

I do like Otto Klemperer Beethoven cycle you reference as a sort of slow tempo inauthentic personalised reinvention of Beethoven. I see his vision of Beethoven similar to a rock/pop artist doing a cover of an artist with a completeley different arrangement and producing interesting results.
Listening to the authentic brisk tempo of the written score of Beethoven Symphony no. 5 first movement is akin to listening to thrash metal while listening to Otto Klemperer sluggish romanticised version is akin to listening to sluggish heavy Black Sabbath. Both interpretations I find interesting