EMEA is easiest, literally only NAVI Liquid and FNC. if one wins sao paulo, ginats and vitality are fighting for the last spot
ASIA: DRX, PRX are the obvious go to, but the third is a tossup between Zeta GE and Talon. GE and Talon all depend on is their individual gambles of their players (Patiphan being healthy and whatever GE is doing hopefully they play 4 of their 5 imports at least). So the safest bet I feel is Zeta. If you're wondering why not GenG, it because in the 1 tourney we've seen of them, they looked significantly worse than talon.
Americas: this is the hardest region for a top 3. While I hope EG does good, that isn't realistic so Im gonna go with NRG, 100T, and Loud