Biergarten does seat you with others, which could be good or bad depending on who you are seated with. I have never been there solo, but I have been seated with a solo traveler who I was more than happy to chat with. The other group at the table ignored my group and the solo, so if we hadn't been there it might have been boring for her. Honestly, though, the most they will do is ignore you, which at that point is the same as being at a table alone, which you would anywhere else. I would just go with whatever food appeals to you most and give no worries to being solo or not. If you are a bit self-conscious about it, Restaurant Marakesh in Morocco seems like it is less crowded, and there are dancers to watch, so that might be a good one.