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.