There are multiple schools of thought when it comes to which forensic tools to use.  Some practitioners prefer the commercial tools, citing the need for support, availability of training and certification, and the number of cases where the tool was acceptable to the court without challenge.  Others prefer open source tools because they can inspect the code themselves to ensure they can defend the tool and that it does only what they want it to.  Some are good enough at coding to modify the open source tools to their specific needs.  Others argue that the cost of open source tools (free) make setting up a forensics lab or company much less costly.

Whatever your preference, check out the listings of tools and make your selections.