Personally I want Raidou more than anyone. He was soooo unique in DOAD. He was a fast big guy. We don't have any fast big characters.
I think Rachel is pretty fast, but I get where you're going.
I'm not going to be disappointed if Raidou was to come because he's one of my favorites as well, but Tengu is more unique than Raidou, and I think that's primarily why he she should show up first.
DOA needs more evil personalities, and if a completely new character is announced I have a big shot at being disappointed when I know I'll be happy guaranteed if it's Tengu or Raidou.