I guess for right now, here's my list (not in any particular order):
1. Nova Prime / Tesla Unread (even though both need updating/fixing for Lollipop
2. Messaging (stock messaging app, since I rely on text messages every day and don't find a need to use a third party SMS/MMS app)
3. ESPN Radio (gotta have it ... it's my background noise almost all day long)
4. Skype (even though MS is making it worse and worse with every update, I still rely on it to keep in touch with a few people who I can't really text)
5. Chrome Browser (because you MUST have a browser on your phone ... the fact that some of you don't list a browser baffles me LOL. NOTE: Realize that with a browser, you have access to Android Central and/or any other forums you may participate it ... as well as facebook, linkedin, pandora, etc. Point being, the browser is in effect a TON of apps all rolled into one.)
EDIT: I just assumed that we are NOT considering apps like the Phone Dialer, Play Store (though it can be reached via the web browser), Contact List, etc. That said, since I prefer the stock messaging app, my listing of that might not be warranted.