Stacker has a very well featured Free-for-Life plan (everything that Circular offers and more)!
We love Circular, but it only posts to Twitter. Stacker posts to Facebook (Profiles/Pages/Groups), Twitter, LinkedIn (Profiles/Pages/Groups) and we are in the process of adding in many more networks.
With Stacker you also get a Universal Inbox that displays and lets you Like/Favorite/Reply-to incoming messages from across all your Social Media accounts in one place.
Which is probably great for your audience, but isn't right for me. That said, I'm probably one of the worst customers for a social app—I'm cheap and I derive only a little bit of value from social networking/marketing.
What I get from Circular.io (and Stacker doesn't seem to offer in the free plan?) is the ability to schedule posts for X twitter accounts (currently, X = 8).
You are right, but with our Amazing plan you can have 2 way communication with your Twitter followers for just $10/month and upto X = 12 Twitter accounts with in-depth click tracking and lots lots more :)
We love Circular, but it only posts to Twitter. Stacker posts to Facebook (Profiles/Pages/Groups), Twitter, LinkedIn (Profiles/Pages/Groups) and we are in the process of adding in many more networks.
With Stacker you also get a Universal Inbox that displays and lets you Like/Favorite/Reply-to incoming messages from across all your Social Media accounts in one place.