Ask HN: What CRM do you use, why, and how do you integrate it with your app?

A challenge that I'm running into while scaling my company is related to customer database management. The app has a customer database and an admin area, but I've found that non-technical employees such as sales and customer success want to do stuff with the customer database that the app's admin panel doesn't allow, such as reporting or adding notes. Over time my engineering team has added some of those features to the admin panel, but I feel that using a CRM for managing the customer database probably makes more sense going forward.

I'm looking for advice. Which CRM do you use, and why did you choose that CRM? The biggest one is Salesforce, and the sales people seem to love it because it has every feature they need, but I'm not so impressed by the UI/UX. It feels like something that only salespeople will end up using, but not everybody else, because the UI/UX feels awkward and complicated. This will put the sales team on an island, which I feel is dangerous.

Who inside your organization use the CRM? Is it only sales people? Or also other roles like marketing people, account managers, tech support people, etc? Ideally I want a CRM solution that everybody wants to use, not because they have to but because it is nice. This way, everybody inside the organization always knows exactly what is going on with a customer which improves business continuity. Does anybody recognize this problem? Which CRM fits this bill?

Finally, how do you integrate the CRM with your app? Is the integration one-way (changing stuff in the app modifies the CRM, but not the other way around) or two-way?