We have hundreds of APIs, and we use RAML + json schema.

Since Swagger (OpenAPI) seems to be gaining ascendancy, I recently (some months ago) looked at migrating off of RAML, but at that time the Swagger guys had a philosophy that they would only support a subset of json schema.

I get their reasons - they want to be able to generate code. But the things they didn't support (like oneOf - needed whenever you have a set of resources of varying types) are a show stopper for many APIs with even moderately complex payloads.

For us at least, its more important to have a single source of truth for our APIs than to be able to generate code from the specs. Hence we remain on RAML (which seems great - just looking like its losing the popularity contest).