Need an AI Product Comparison Engine built.

We need an AI-based product similarity/recommendation engine built for our SaaS marketing automation software. The engine will need to take in details of the product being marketed, and produce a list of similar products, ranked in order of similarity. It needs to be multi-tenanted, so each customer has their own private data. Sounds simple enough, however the process of evaluating similarity involves comparing visual appearance, features, benefits, location, inferred buyer personas, and other evaluation criteria which may be user-defined. We also need the engine to learn from user feedback and rerank accordingly, per tenant. It must be secure and available to our SaaS application via an HTTP/JSON API. It doesn't need a user interface, our SaaS product will handle that. But it does need to be fast, secure and scalable. We are looking for someone to perform the initial build from our spec and then maintain it over a period of time. If this goes well, we have several other projects that require similar engines.