I am posting this for Aparna M. http://sharepoint-community.net/profile/AparnaM
Hi Aparna,
I am assuming that in general you are basically asking which product is the best as a 3rd party product for workflows with SharePoint. I have never used Agilepoint so I do not know much about that but but I have used K2/BlackPearl. I think you can do a lot of programming and customizations with K2 but to be honest, the project we used it on really bombed and it was very slow and full of bugs (although this was with SP2007). I have used Nintex some but not extensively, most people in the community I meet like Nintex the most but I think you should ask for a demo from each company and make a specific list of exactly what you need the product to do so you can evaluate each program fairly.
Others feel free to chime in as well.
Matthew
