Hi Logie101,
I think... The world is your oyster!!! So many options, such a vast price range!
I personally have a Nikon D5300. I am no photographer, I just enjoy taking a few snaps and enjoy them on high quality screens / professional prints. I find the quality fantastic, and the definition pretty impressive - but then again - I am no photographer. Just an amateur using a kit lens!
A few friends have used the Canon 5D and 6D with really nice lenses in the plane. This is far superior to the quality of my camera, but I find it is wasted on the fact that the average spam-can has scratched/damaged windows. (I also didn't have that kind of money to spend on a camera). They however smash my little Nikon to pieces when you compare the quality whilst taking pictures with the window open! You will however see day and night differences between your iPhone / Android phone's camera - mostly because of the focal points and ability to use real zoom.
I would recommend getting polarising filters, they are super cheap on Amazon (check you're buying the right size) as this will help with the amount of reflections that you see whilst taking pictures from inside the aeroplane.
I am happy with my little camera, i love the pictures it takes, and have printed a book of my travels with it too. Absolutely perfect for what I wanted. If you want full comparison of available cameras, there is a funny channel on youtube (which calls themselves "The Top Gear for Cameras" DigitalRevTV) [
http://bit.ly/2e3yaDI] who do a pretty good job of comparing different cameras.
I hope this helps!
Alex