@Elektrik:
Mmmmmm you might need to lower your expectations a little bit. Try more like 26 max. This is a brand new game series after all, they have to create all the assets from scratch, so it may take a couple sequels to see all the characters you want.
As it is, we already have 6 (possibly 7) characters with Ace, Sabo, Croc, Doffy, Eneru, and Luffy (with pre and post timeskip). +8 Strawhats makes it 14 (hopefully they limit it to only post timeskip). Then +4 admirals is 18. +7 Warlords (Law, Hancock, Kuma, Mihawk, Jimbei, Buggy, Blackbeard) [Highly doubt Moria makes it in]. We're already at 26 and we still need Whitebeard. So 27 characters are a definite must have. After that, additional characters could go either way, like Smoker, Lucci, Ivankov, and Shanks
Let's start more from what we saw than what we wish. This seems to be a game centered on devil fruit, with a special concentration on the Post Timeskip and some boss from pre. So my guess for the unforgettable is:
Luffy (Post; Pre)
Doflamingo, Caesar, Law, Smoker
Newgate, Ace, Marco, Teach
Akainu, Aokiji, Kizaru, Fujitora
Rutchie, Enel, Magellan, Crocodile
Hancock, Kuma, Buggy
Sabo, Kid, Drake
Even so, I think they'll aim to put an equality between fruit types (same amount of Zoan, Logia, Paramecia).