Let's see I have a compass, a scientific calculator, flashlight, Pandora, youtube. If I could find a swiss army knife app I'd install it. What else should I put on my smartphone?
Well, a map/navigation app is probably up near the top. This should be pre-installed on your phone anyway. A sync app to automatically upload your pics to cloud platform. A good calendar app like aCalendar. If you feel your phone getting hot, you need a feature to squelch the auto-start apps - Security360 is good.
I hate too many apps, my favourites the flashlight banking apps whatsApp skype favourite news apps evernote you tube music Aldi (specials) app dropbox for pics and other minecraft for the kids and a few other games Twitter/LinkedIn Fire Ready (Fire alerts for my area) calendar app
Got to have maps, but I try to only use it if I'm flat out lost as I don't want to rely too much on GPS. Amazon, but this app can be dangerous if your drinking (trust me I've had (*)(*)(*)(*) show up and I'm like when the hell did I order this??) Brain games are great! Calender, Chrome, Calculator, Clock and Email are all stock so most have those. Social media apps of course. Banking and Wiki app. Some randoms: Red Cross First Aid app, radio streaming apps, and an IR app if you have an IR blaster for your phone.