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 experience is super fast. A simple one click copy/paste from the site made it simple to implement in my original contract. Review collected by and hosted on G2.com.
Law Insider shows you "everything" - which is great if you know what you are looking for but can potentially be daunting if you are not quite sure what you are after. I think telling people what clause to use would be considered legal advice so their algorithm surfaces what is the most relevant result and leaves it up to the user to determine if that works for them. This is fine for my purpose, but maybe others might find it challenging. Review collected by and hosted on G2.com.