Regarding ease of M slices, definitely the Tengyun. I just did a bunch of H, Z & U perms on my GuHong and it wasn't as effortless as I originally thought after a side by side comparison. So take that recommendation with a grain of salt. The Tengyun on the other hand never disappoints in this category.
In general also the Tenguyn. I am really enjoying the GuHong for speed solving right now and it's super light feel is really agreeing with my turning style; i've done hundreds of solves on it lately and its been my main over the last few weeks. I mainly use my Tengyun for casual and BLD because of how quiet it is; not sure why i've restricted it like that in retrospect.