How can I choose a specific circle for the default stream in Google+ ? Many extensions don't work, and are not comfortable if using another PC.
Streams of Circles are just web pages, you don't need an extension to do this.
I hope that there will be a feature in Google+ to do this.
But what I do is that I copy the link of the circle, it will be something like this:
https://plus.google.com/stream/circles/p6a5598f68a00498712 , and I add it to Bookmarks.