I tend to write programs for portrait mode and usually forget about someone running it in landscape mode. I use portrait because I code strictly on the iPad and it shows more of the code with the keyboard. I tend to keep lines of code short to avoid any wraparound. So the question is, do you prefer portrait or landscape and should code be written to support both. Or does it just depend on the program.
I’m the exact opposite. I use a fabricskin case/keyboard so I’m always in landscape. I always forget about portrait. I’d say it’s a good practice to support both when it comes to utilities (I should take my own advice!). As for games I believe it greatly depends on the games design.
@dave1707 i use ipad in landscape only. Most of the time i just comment out your first line that sets the supported orientation to portrait only 
and it works fine in lanscape
I use my iPad in landscape for the majority of the time, from reading, watching movies, and especially coding! I find for games landscape is used more often (thumbs can easily get to the side of the screen without obscuring that much), but for games that require you to directly interact with the screen (cut the rope) I prefer portrait. If you have any typing involved I would quit and delete your app ASAP if it was stuck in portrait!
Landscape
I always use landscape mode.