i use hybrid.
paper for my current projects list, and action lists,
i organize reference information on either paper or freemind mindmapping software .
i use basic tools and so its free to evolve and it does keep evolving !...its like seeing a kid grow..
why should i limit my gtd tool to the imagination of the person who designs a gtd software.............
i mean ...if i use a digital gtd tool.....it wont evolve...right ?
and i cannot tweak it ..as i am not a programmer.
paper works great for me........as i use a lot of sketches and colour pen markings.
if you dont like the answer, change the question.