OP, I'm right there with you. I love my truck. Seats are great except for the headrest. I have been on a mission trying to resolve the issue.
Im 6' 0" 160lbs and lanky (no shame in that game). My seat is slid back almost all the way to not have my legs bunched up and to have them supported by the front of the seat bottom. The seat bottom is tilted up 100% in the front and down 100% in the back, placing my a$$ as far from the headrest as possible. I sit more upright than not because the steering wheel doesn't have a telescopic function, allowing my arms to not be straight out and causing strain on my shoulder and neck. If I remove the headrest, I can lean my head back enough to be comfortable, but its not safe. Spin the rest around and no bueno on the safeo also. $#!+
Here is my quick "research" (AKA: screen shots and easily available comparisons over the last two days.)
First pic is my truck, crazy slant forward.
Second pic is my headrest next to a 2014 versa note. Thought I had a winner but the metal rods were more narrowly placed the versa seat compared to the frontier
Third is the 2014 titan, crazy slant forward didn't even try to fit it.
Fourth is a 2005 armada, looks just like my friends 2005 titan. Im going to test fit next time I see him. This is the best looking option so far. From other posts I have read on CF, the seats bottoms are interchangeable, so maybe this will fit.
No picture of this one, but I went to the Nissan dealer to get some work done on the truck. A 2017 titan seat received my headrest!!!!!!!!!!! This will be the hardest find and most expensive of all the other headrests to get, but it fits and does not appear to lean as far forward as the frontier's. It looks more like the earlier titan/ armada style.
Also read on CF that the 370's will fit on the frontier.
To me, the holy grail would be one that tilts forward and back. My dad has a Lexus RX with this feature and I love it. So my thoughts here are to look into the Infinity version of the Armada (XQ56 or something, too lazy to look it up now) to test fitment.