iPhone 6S Plus for social media. My first real use for a client was on a political campaign I worked on. The client wanted images posted live on Twitter, Facebook and Instagram while the candidate was speaking. The iPhone solved that easily.
When I need more than what my iPhone 6S Plus can give me I turn to my Nikon D750 and use the wifi options built into the Nikon D750.
On my iPhone I use the app Camera+ as my primary camera how ever the iPhone camera is a powerful tool on its own.