I converted to Windows phone from Android two years ago and loved it. I still really like the Windows phone. Two months ago. I converted back to Android. I went with the Note 4 specifically for the S Pen. It was a tough decision but I had to do it.
If you are into inking like me, then I think the Note 4/Surface 3 combo is the best combo for getting work done. I'm in sales and take lot of notes. I had the HTC 8x and my Surface 3 before. This was a good combo as my notes on my Surface would sync with my phone. I could view my notes on my phone. In meetings, I would whip out my Surface and take notes to the envy of Mac users. You can lay the Surface flat and actually take notes while looking at someone in the face and not have them wonder if you are really listening or just surfing the web or answering emails. But I digress...
While my HTC/Surface combo was good, I found that I was reluctant to take out the Surface in lunch meetings. Most of the time, space was limited and the Surface was too big to whip out and start writing. My HTC wasn't any better. While it had OneNote, there was no pen and I would have to use the keyboard. I ended up relying on memory or taking notes on napkins. Not good.
When my phone upgrade came up, I was set to buy another Windows phone. In the store, I noticed the Note 4 and saw that it has an S Pen. The light in my head turned on. I checked to see if there was a OneNote for Android app. Sure enough. Next, could I write notes on my phone and have it sync with my Surface 3. Check. Dang, I had inking nirvana. Now, I can use my phone when space is tight and I use my Surface when I have more room. Best of all everything syncs up.
Long story shorter, I am productive in any setting. I just wish that there was a Windows phone that had a stylus. When that happens, I will sell my Note 4 and go back to Windows phone.