I'll give it a try, gearing up for a DJing gig in Italy I have to deal with these issues anyway.
So this doesn't get too unwieldy, I'll do single posts for each of the 4 orhcestras mentioned.
Some people seem to regard Di Sarli as simple and straightforward. I can't quite agree on that view, as his music has great depth and complexity. However, it is quite danceable for beginners, too, as evidenced by its frequent use in beginner classes. Di Sarli's strength lies in the fact that the same tracks that are quite easy for beginners to dance to (due to the relatively clear beat) are at the same time challenging and rewarding for seasoned dancers who can squeeze much more out of it. Add to that the fact that Di Sarli has recorded from 1928 until 1959, and you have a wealth of markedly varied music that can fuel a wide range of moods. Rhythmic, lyrical or dramatic - Di Sarli delivers.
Furthermore, I regard Di Sarli as the greatest of the Golden Age orchestras. If I were to pick one orchestra to demonstrate what tango is, and can be, Di Sarli would be my pick. It's iconic.
From a DJ's perspective then: I always find it hardest about the job to pick what *not* to play, something especially bad with short milongas (less than 6 hours or so). Only one tanda of Di Sarli during the evening? Impossible. Two? The bare minimum that still leaves me with tough choices. My first pick is usually Rufino, as I can't really not play him. But then you still have Podesta, Duran, early instrumentals (Sexteto) and at least the classic 40s instrumentals clamouring to be played. And let us not disregard the 50s stuff - at the right moment in the milonga those can be exceptionally good.
So with a 5-6 hour milonga I usually end up playing at leat 3 or 4 tandas of Di Sarli, not counting valses (sometimes Di Sarli makes the cut there) and milongas (rarely makes the cut).
Shall I go on or are you guys bored already?