I'm only going to talk about 4 clans considering there's 16 i think that's fair and I'm a clan leader so i'm more likely to be biased
Rebels- very high chance of winning they have some of the best team work in MCSG and have some great PvPers
Rivals-frankly i think they're over rated i don't know if it's because they hate my clan (React) for no reason or not but even though they have a lot of players with over 1000 wins they really aren't that outstanding
Hunted- i've talked to several of the hunted's members and it sounds like they're incredibly unorganized, i've never been in there TS because, well, they don't have one. they only use Skype to communicate and, something with they hunted as rivals, just because you have members with over 1,000 wins doesn't mean they're that good.
SectorSix-(my favorite) some of the best players in MCSG there only down fall is that they lack in team work which sadly is a key point in clans, from experience while React was scrimming them they seemed to all go separate ways and meet up later but i feel like if they're put in a map that none of them no and they have to study it to find a chest route i feel that that problem will be fixed and they will have a very high chance of winning clan wars season 2!