has anybody used any other Form building solutions (FormAssembly, FormStack, SalesForce Forms or anything else) other than "Sitecore Forms" with Sitecore? Sitecore Forms require xdb for reporting but I want to run Sitecore in CMS only mode.

So, can you share your experience with another Form building solutions that integrate well with Sitecore? I am looking for a Forms solutions that is easily customizable (in terms of design and validation) and integrates will with Sitecore.

Tried FormStack, not so good in terms of integration.