The best criteria for the success of a process asset library is its user acceptability. Is it inviting enough to attract users for browsing it? Is it friendly enough to give maximum information through minimum clicks? Is it having the characteristic of one document flowing into the other or one data leading to other?
My suggestion would be to evaluate the tools on the basis of the criteria as identified in the questions above. Some more criteria can be discovered after brain-storming. A formal DAR will give a solution.
My impression is – after all this – you will be inspired enough to develop a customized tool for yourself.
I may not name any specific tool as you can easily get their names by some web-surfing. However, make sure that you do not start getting driven by tool formalism and start thinking the way tool makes you think.