I use Lua Patterns where possible. I find them easier to work with than most regex libraries and they have the little bit extra that makes them not a true regex but the extra you usually want (matching things like parens).
The best thing about knowing regexes, in my opinion, is how it helps with refactoring. Got an assignment the wrong way around? s/\(\w\+\)\s=\s\(\w\+\)/\2 = \1.
s/\(\w\+\)\s=\s\(\w\+\)/\2 = \1