Most of the scripts that I use are ones that I've written myself, or with assistance from other scripters. NNScript seems to be a popular one, but I'm not familiar with it, so I can't honestly give an opinion as to how good it is or not.
I'd suggest you check the different scripting areas on a few of the other mIRC help sites. Most of them have some kind of a ranking and/or area where comments can be left. Hawkee mIRC Scripts
There's a couple of links to other sites, and each of them has links to other sites as well.