S Tier: EU
A Tier: NA, CIS
B Tier: BR, TR, KR
C Tier: JP, OCE, LATAM, SEA
EU is strong overall region so I gave them S tier.
NA only has 1 contender (SEN), but a handful of other strong teams that suffer from inconsistency (100T, NV). C9 and V1 looking decent = A Tier
CIS, the game isn't that popular there yet. Gambit is quite strong though, up there with the best EU teams. So in reality, it's Gambit that is A Tier.
BR I don't really know, will have to wait until Iceland. They could be A tier.
TR just got slapped by EU, Oxygen still took out Guild, so I gave them B tier.
KR is kinda top heavy, and their "best" team is a bunch of tier 3 CS pros. So I gave them B tier.