I've finally got around to using Bergger Art Contact as it's supposed to be used - not as a slow enlarging paper, but as a relatively fast contact paper.
I developed in Ansco 130, which seems to have been a good choise.
I'm converted. My 5x7" camera will see a lot more work next year - this was amazing (not that the paper is poor as enlarger paper)!
I have never tried Azo, nor seen good examples of it. I do however have a fairly good selection of prints from around 1870-1920, with examples practically all the popular techniques of the time. I still say the Bergger paper is very, very good.
I may try Azo. I may try albumen. But I might just decide to save my money towards an 8x10" camera...