Finding the perfect script

Hi,

I wasn't sure where to post this, but since it is related to search engines I thought I would get better response here

There are a lot of search engine and directory scripts out there. It gets very hard when you are trying to find the perfect script to run an online directory.

What are the things you should look for when you are looking for a link indexing script considering the back end and front end of the script? Price is no object.