What is the best BPM (Business process management) server ??

there are alot of business process management suite it is difficult to say that the x tool or softwere is the best one but according to your business need ,Below are some of the best software in my opinion* Processmaker* Intalio* Bonita BPM * Activity BPM

I used K2 Blackpearl for a while.
It's very powerful BPM.
It is currently the only product fully integrated with SharePoint and other Microsoft products ex.
Infopath and Outlook.

Business process management (BPM) is a systematic approach to making an organization's workflow more effective, more efficient and more capable of adapting to an ever-changing environment.
A business process is an activity or set of activities that will accomplish a specific organizational goal.