Tracker is "the" model for corporate legal matter management in the SaaS (software as a service) space. It is very easy to use, low cost, and can generally be configured to a given legal dept's needs. That said, if massive customization or deep integration with existing, internal IT infrastructure is necessay, Tracker probably isn't for you. But if you need a easy to use, clean, low cost, and stand-alone system (that can 'push' data to other systems), Tracker is definitely a product to check out.
LawManager is a highly configurable, some might say 'customizable', corporate legal matter management system. Bridgeway picked this product up via acquisition, and seems to have found a niche in the government space with it. Given the ability to configure/customize, it is possible to create a system that is less easy to use than the 'standard' interface. But so long as some thought is put into the implementation, LawManager is a very stable and easy to use matter management system.
If you are willing to put some time and effort into the implementation, TCE can be a very robust case and matter management (MM) system. Like many commercial MM systems, it is highly configurable. Earlier versions left a lot to be desired out of the user interface, but more recent versions incorporate a lot of AJAX and present much more cleanly.