What are your requirements? Are you looking within a specific price range? SaaS or on-premise? Do you need it to integrate with any of your existing systems?
Hi Ken, James definitely has it right on with wanting to know what you're needing. Just having the quantity of users doesn't help narrowing it down.
However, I can help narrow down to one choice that should work for you if you have basic needs: JobNimbus is a full, free CRM (subscriptions available for additional features as necessary, discounts available starting with 10 or more users), cloud-based, and powerful.
The biggest thing is it's simple. I mean dead simple, simpler than any CRM out there. If you are worried your team will have trouble using it or will fight against it (they will, 60% of CRM users do) than this would be a safe bet.