I'm not sure who in particular I would like to see, but I definitely know what I don't want to see in any way:
- characters that are obviously from different era or radically different setting (SW characters in Soul Calibur; granted, SC is a crazy circus enough for a lot of stuff to be there, but SW is just too well-known for me to ignore that even during this mental gymnastics of "pretend you don't know them", lol);
- characters that aren't known for being the type to seek fair open fight with their equals (Alien and an assortment of serial killers in MK; possibly Negan in Tekken) - they can look fitting in a game in question, but such inclusions mostly don't do justice to characters themselves;
- characters who are associated with distinctive artstyle of their source work, unless they are somewhat adapted for DoA - this one should be self-explanatory.
I generally prefer guests who you won't be able to tell from game's original cast if you don't know much about DoA or works those guests are taken from.
Most of DoA5 guests were like that (martial artists with "tournament fighter" and "some weird ninjas or something" background, copiously represented in DoA).
Geeze Howards in Tekken, for roughy the same reason.
Soul Calibur's Geralt and Ezio are decent examples (characters from late medeival / low-ish fantasy settings in a game that draws a lot from medeival and maybe even early Renaissance era).
Possibly Predator in MKX (considering that some of game's original cast's aesthetics were drawn from him, plus he fits well into modern day setting with a lot of military types in it, referencing original film).
Common suggestions in this thread would be fine, IMO. I mean, sure Tifa comes from very different world, but you wouldn't tell by her appearance. The rest fits to a T.
