If you want a specific CRM solution for your company, anything that your are comfortable with is fine. If you want to make it a platform, and a generic CRM solu

If you want a specific CRM solution for your company, anything that your are comfortable with is fine. If you want to make it a platform, and a generic CRM solution that other companies can use, you need to think about APIs, security, customizations (custom entities, custom fields, relations, customizing UI), multitenancy (if you want a hosted solution). The list goes on. If latter, I would probably choose vuejs/Play2/MongoDB. (Replace Play2 with RoR or Django or anything else).