I like em both, but I think the Zx could do with more work here and there.
I also fancy porting modern visuals to old computer limitations.
I have done many mock ups, specially with the trs80 color.
I´d wish I could release the Avocado game with a set of look-like oldies gfx to go along as well as a little instructions on how to mod the gfx oneself.
But that has to come ´after´ the game is released.
I will dig some of the exemples I did and post here too later.