Faiss and Pinecone are at the top (disclosure: I'm from Pinecone). But Faiss isn't really a full-fledged vector DB. Pinecone is a managed option which is out of the question for a company like Twitter and maybe for you (although you should consider it). After that comes Chroma in third, and then Qdrant, and then Weaviate.

Chroma has a big following by virtue of being plugged into the AI ecosystem in SF. Qdrant seems to be doing great work but their location in Europe is probably not helping.