My bias is towards PaaS compatible implementations (i.e. no full LAMP server required). Russell Beattie has the definitive and updated list of all readers right now: http://www.russellbeattie.com/blog/readerpocalypse-the-players
- Stringer - Ruby-based reader - Sinatra, PostgreSQL, designed to run on Heroku
- Leselys - Python / Mongo / Redis, designed to run on Heroku
- CommaFeed - Java + AngularJS + MySQL, runs on OpenShift
- BirdReader - the only Node-based feed reader I could find. Uses CouchDB / Cloudant as the DB, no instructions for PaaS hosting