Alliance and Fnatic for EU.
Curse and LMQ for NA.
The vote to Curse might be strange, but they've been very strong against all the top teams in NA recently, and unless CLG comes back and surprises us with their practice in Korea, I think Curse has what it takes to beat CLG, move on towards playing C9.
C9 vs Curse will be the clincher, as both teams are playing at their best for the season, but I feel Curse has more variety while C9 relies on overall strong mechanics they're easier to surprise or be shaken by non-standard picks and play.
LMQ vs either TSM or Dignitas should be in LMQ's favor, TSM and Dig have been horrible recently and I doubt the week off will reignite them.
Alliance and Fnatic should be shoo-in's, The other 4 teams in play offs have been rocky and performing poorly, Roccat has never recovered after teams learned how to play against a 1-3-1 or execute it themselves, so they're just a mediocre team. SK Gaming and Millenium have been shaky, SK's mid laner Jesiz has been playing poorly, while Millenium's whole team EXCEPT their mid laner Kerp have been under performing.
The only potential upset is Super Hot Crew, as they tend to randomly play good on some days and suck on others. Most likely though, the seasoned teams who are used to the stress will survive and win the series.