I tried playing with a keyboard, but nothing beats the controller. I don't think it's because I'm more used to the controller, I really believe the controller is completely superior.
I would have to say a controller feels better and controls more naturally for me when I'm playing GTA. The keyboard controls when using a keyboard can get very complicated once flying becomes a part of the game. I remember not being able to beat a particular mission with a toy plane because I had such a hard time flying it.
To me it goes down to what i'm playing, i prefer hacking, punching and slashing with a controller, while FPSes are more of a Keyboard thing in my opinion.
It really depends on what controller you use. If it's a PlayStation controller, then you are more likely to enjoy keyboard than that piece of ****, sorry for the vocabulary, haha. If it's XBOX, you're going to love it much more. Though I only use keyboard at the moment, because I only play on PC.
I love to play with the XBOX controller. It feels much more natural than the keyboard plus the controls feel much fluid and nicer. It really depends on the person though.
I've tried using the keyboard, but to me there's nothing more relaxing than laying back and holding that old school controller wanting to play all dang night. The keyboard is great and definitely a nice switch up, but the comfort, and pure nostalgia makes the controller my favorite.
I've never played GTA on a console before; always on the PC, so I can't tell the difference. However, I do have the opinion that, just with the number of mappable keys alone, the keyboard is my preferred choice. Mesh it up with a mouse, and there you go; perfect especially regarding combat. The flight schools are really hard if done in a wrong way, but usually, once you get used to the controls, or made a few tweaks like mapping rudders or the turning (not the wing movement) closer to your WASD movement, in my case placing it on Q and E, it'll be easy. I do wish I have some knowledge on how it will be done on controllers though.
I hated those flight school missions so much. They were so annoying. I completed it with a keyboard, but it is definitely easier with a controller. Seeing as I also played it on PS2 and completed it, not easily, but easier than I could on computer.