It's always tough to give a recommendation for any product, we generally steer clear of recommendation type questions.
If you have questions about specific features or whether in peoples' experience certain features are more desireable than others, or what to look (and not look) for, we'll be happy to entertain those.
Here's what I consider desireable:
-flexibility to easily turn cloaking on and off
-multiple methods of detecting spiders
-logging, so that you know the script is working
-notification of spider visits (a nice to have)
-logging spider visits for trending analysis
-the script does not use redirection to serve pages
-if you don't want to get into editing code then a GUI interface is nice
-IP address updates included
Here's what I consider undesireble:
-scripts that redirect users or search engines
-scripts that use templates to create pages
-scripts that force you to configure parameters for every page
This is all IMO of course.
Are you solving a particular problem with cloaking or is it "just" a measure of flexibility you want to gain? It may make a difference in what features are desireable depending on the reason (maybe, maybe not :) )