Rob, the guy who is doing my barista training (update about that to follow soon) told me I had to go here. It's supposedly the most elitist shop in the city. We went on Sunday before going to the Flomarkt across the street (totally recommended - so awesome for finding cool knick knacks and people-watching) I waited about 15 mins to be served, the shop was PACKED. It did give me time to look around, which wasn't difficult considering it's about the size of my bedroom.
Bonanza is also a roastery so I bought a bag of their beans too, need to crack on with those after I finis the Phoenix. I think the baristas were Australian but it was hard to tell... one was maybe Dutch and looked epically Aryan (plus point for Bonanza, keepin' it master race). I also spied a bag of Blue Bottle beans but didn't wanna bother them by asking for that as my espresso because (a) busy as fuck and (b) intimidating as fuck. Good sign though.
The coffee was great. #2 of the 3 we visited. Very smooth and went down nicely while walking through the Flohmarkt where I searched for sketchy pin badges and bought skull related objects. I would say go to Bonanza during the week when I am sure it will be a little quieter. Don't expect to be able to sit down though.