From what I've read, JTK are constantly improving the legends with each new batch. I've seen a set of black on beige JTK keycaps in person, and they are really nice. (I am a connoisseur of original Cherry keycaps and to a lesser extent of recent GMK keycaps).
GMK legend consistency is not great either: very bold M relative to the normal N next to it, for example. B is on the bold side. Plus all the light colored keycaps I've gotten from GMK so far--other than older WEY keycaps--have pretty bad LED light bleed-through.