I personally favor C9 and feel their style works best internationally. Basically, I don't think a sudden meta shift or something is really going to do much to them, nor is a massive change in how their opponents play. Rush's Lee play today was terrifying, too.
CLG's problem is that so far, we haven't seen this "just let Darshan splitpush" style work out internationally because Darshan just isn't as good as the god-tier tops like Smeb and Ssumday (RIP MaRin). They'll do well in NA for sure, but I'm actually curious to see how this Trick2G-style gameplan works against KR, TW and EU teams.
IMT is still NA's best team right now, by far, but what worries me about them is that they look like a team that could utterly collapse from a meta shift. So far, they've only shown proficiency on a single style: Protect the Turtle with Huni on a counterpick and Pob on a utility mage. Every single game. Turtle's Ezreal today was good, but not the kind of hard-carry stuff he had on Lucian and Kalista, so when those two champs go out of meta (or even one of them) I really worry for them. Equally disastrous would be if Reignover keeps playing like he did today (he looked tilted, making uncharacteristic missteps and whiffed ults) or if non-utility mids become really strong (assassins or burst mages).