From the beta, Parappa. I'm really good with him and like playing as the character a lot so definitely going to keep using him.
Going by the gameplay videos, the additional characters are probably going to end up being Toro, Dante, Cole, and Evil Cole. I'm going to use everyone, so not going to just take some impressions of videos I've seen of them, but these look like the ones I'll end up with.
By gameplay videos? Jak, Ratchet, and Good Cole look promising. I also really like Sackboy's charm and Drake's hilarious moveset.
Honestly, I REALLY like every character besides Fat Princess (I am indifferent with her).
Welcoming Committee- "The business of gaming is business"
Sly Cooper (loved him in the beta, favorite video game character)
Nariko (bada⚡⚡, great character)
Ratchet (immediately recognizable nostalgic character to all)
Cole (I like suckerpunch because of sly, and Cole seems really cool)
Nathan Drake (dat hilarious moveset)
And of course the DLC characters.
Sackboy and Drake. I may also continue playing a lot with Sweet tooth because that Starhawk pre order suit looks pretty dope. I imagine I'll also get alot of play time (heh) with Nariko too.
Studies show it is humanly impossible to play through all online content in LittleBigPlanet in a single lifetime on Earth.
Don't Forget to Play [Persona 4 Golden] Every Night Before Bed.