I'm a hybrid of planned and inspired.
I find that I love storytelling that uses a lot of foreshadowing. That requires a pretty hefty plot writing preparation. I spent 2 months just writing (built on 3 years of inspiration) for my comic Aetherwar. BUT when I started drawing it, a lot of scenes changed for 2 major reasons.
Firstly, comics aren't pictures of writing. A comic page is a composition in itself and has powerful tools unique to its medium. So some written scenes which were exciting and fine to be read, were either boring or extremely long winded in comic format. The change was practical.
Secondly, between the written draft and drawing, other ideas often happen to me. Better ideas usually of what I'm trying to achieve in a scene. Usually that would be a character trait or a plot device.
Which is tricky because it can fundamentally change the story and I have to run back to my plot sheets (of which there are several iterations now) to cross check that each thing is well paced and without plot holes. At least as far as I can see.
Once the pencils are down, the art process is straightforward. Pencils, ink, colour. All done digitally. After that the final touch is to just clean up the dialogue. Often times things can be said simpler and more effectively than even the fifth draft. And that's about it!