I want at least one of these two. Let's go!
I'd be very happy with no guest characters and I believe they do weaken the franchise, due to removing player continuity between games. Like ONI might not be in SFV but was in other SF over the years.. when he comes back that is hype for fans fo the franchise.. when people get into MK on a guest character, it is all lost fandom.. they have nothing to hype for in a future game as that character is never coming back. Just look at EvilRyu reveal for an example of how when you have a huge roster using your own IP has the same effect as a guest character.
BUT... guest characters are a thing, so deal with it. Sure it would be better without.. but if we gotta have them..
I have to say that Ash is the perfect guest for MK. He has the horror roots, the humour of the character matches perfectly, the way he talks is perfect for into dialogues , he fits the gore requirements, has cool weapons with the shotgun and the chainsaw to make interesting attacks... IMO, there isn't a single guest fans have suggested that is as perfect a match as Ash.
Fatality on Dark Raidan - "Good? Bad?.... I'm the one with the gun,"