I used a cheap round one from the r/v place. about 6 bucks... It is turned off and on by a switch near the door.
I also have a reading light on each side near the head of the bed (we sleep head at the back for dog reasons).
I went with round as it is easy to align (as in, there is none). I tried a square one in another tear but just couldn't get it lined up from every angle. Round worked better for me.