This application has my recommendation! I have used all sorts of regex helpers and regex buddies, both online and offline, but this one is the easiest of all to use. One of the biggest problems with regex is that you can't remember all the tokens. Expresso has a built in tester, validator AND visual builder, the combination of which is rare to find in a single application. It also has a library of regexpressions, and you can save your sessions. It has a local help file!
This regexer gets a score of "Very Good" for "Ease of Use" - because I think it is the easiest to use of all the regexers. You can visually see all the tokens and all the options. No regexer is really "easy" to use, but I couldn't imagine how to do it better than Expresso.
Also, note that you DO have to register the program, but as of the time of this review, the registration is free.
License: Free Details...