Here’s a post where the answer to the above question is discussed 🙂 Here ChrisOC is making the points about K2 blackpoint and elaborating on the discussions we had at various sessions.
“As was shown at a recent SharePoint user group meeting, there are a number of workflow solutions out there, with Nintex, Skelta, and the Microsoft offering of SharePoint Designer and WIndows Workflow Foundation (WF).
The K2 blackpearl product stood out as the better choice for an enterprise scale workflow & BPM tool, with Nintex looking rather appealing as a SharePoint-only solution.
That’s all changed now, with K2 blackpoint as the best choice for SharePoint workflow.”
check this out