Trello is usually the first CRM-like experience I suggest for small clients who need a quick way to process leads from forms or chatbots. It can be easily connected to Chatfuel / Typeform or other form builders via Zapier or Integromat. There’s almost no learning curve. It’s a simple Kanban Board with basic but powerful features. There are also a few add-ons you can get either from Trello or third-party providers (incl. Chrome extensions)
to be honest I’ve never subscribed to a premium plan with Trello, always satisfied with their free offering but it makes sense to open your wallet if you need extra features liked unlimited boards per team, custom fields, voting or third-party integrations (even if you can use Zapier or integromat for that purpose)
SMB owners who don’t want to invest time and money into a fully fledged CMR solution. Trello is easy to use even for non-tech-savvy people. I advised it for dieticians, beauty salons, artists, etc. It’s an all-round kanban board which makes it easy to organise team work or personal projects.