Law Insider seems to have the greatest quantity of both contracts and clauses. I had a specific need for a creative services agreement and I was able to find hundreds of potential clauses to include. Finding the right clause was pretty easy and the website exerience is super fast. A simple one click copy/paste from the site made it simple to implement in my original contract.

I found the site easy to use and contained a lot of relevant data available that can be filtered. There is also a good amount of help and getting-started support.

I can easily find contract clauses to compare against drafts or to help construct drafts if I am building one from scratch. The contracts can be great templates for a starting-off point. It is very helpful.