Ask HN : The best CRM ever developed

I began to use Olark as a paid user recently and it changed my way of working. Before, I was focusing on "development" thinking that clients would come. Now, I am focusing on clients so that development will come. Olark helped me in that turnaround.

Now, I'm looking for the best online CRM to help me keeping track of everything about my clients. I'm currently using ZohoCRM but I'm not completely satisfied. The UI is hard to use. I also tried Highrise but wasn't satisfied.

What I'm looking for : - An email that I can BCC to for email conversations with clients

- A simple read/write API (ZohoCRM API is read-only)

- A simple UI

- More than one user

- A fair price (~20$/user/month)

Let me know what you're using and why!