I limit my intake because of the sugar content; but you are right. There are several club mate alternatives including bio mate, fritz mate and probably a few others that are widely available in Berlin and look and taste similar. I'm not very fussy about which I pick but I tend to prefer club mate. Like many soft drinks, a lot of the popularity is marketing driven of course. It's like pepsi vs coca cola. Always a bit disappointing when you order a coke and end up with a pepsi. For some people it's the other way around of course.