Let's start with the easy stuff:
Tokugawa.
Boy, did he get shafted. His land sucks, and with his capital 3 tiles from the coast, half of what little there is will be left unexploited.
Conflict with JC seems inevitable, and if it's 1v1, he'll lose and may end up FTD.
But even if he gets help and JC bites the dust, he won't have broken out yet: it will be the same situation again, with whomever helped him dismantling JC as his new, stronger gaoler...
Bottomline: the hole he has to get out of is so deep that while most other AIs here play for the win, he's playing for an invitation to the wildcard game.
Things don't seem much better for his neighbour,
Julius Caesar.
No Copper, so no early build-up, leaving him very vulnerable to an early, deadly, 1v2 situation. I can very well see an early attack by Willem (who will have early Copper units), combined with a backstab by Toku, leading to an early elimination. Or JC attacking Saladin, backstabbed by Toku, piled on by Mehmed. Etc.
Even if he escapes an early elimination, he'll need to conquer Japan before anything else, and I doubt it'll be a fast conquest. When he's done, he'll be in a decent position... for a second place finish.
A win seems out of reach here.
I believe all five remaining leaders have a shot, though.
Saladin's seems by far the longest shot. And while him winning wouldn't be a shocker, I think it's very unlikely.
For the simple reason he should die in most games, and be the first to do so in quite a few of them.
He's very likely to found one of the first religions, with the other one going to Brennus. If it doesn't go to Brennus, it'll go to Mehmed or Willem. And Willem could also go for an early Monotheism.
So Saladin will have border tension with 4 other AIs (Mehmed, JC, Willem, Brennus), with a quasi certainty that some of them are going to be on the other side of the religious divide: he's dogpile meat.
Now, if he gets lucky with the religious situation and survives the early game, he's a decent leader who could go all the way. No second place finish for him: he'll win (unlikely) or die (very likely).
Now, his neighbour,
Brennus, is a different story.
First look at the map: his land may not be the highest quality, but there's lots of it! Then two expansion opportunities (Saladin, dog-pile bait, and Darius the Disappointing) to really get rolling.
He looks like the previous' game Kublai... but he shares Boudica's main drawback from that game: he's very likely to found an early religion... and remain its only follower.
So he'll do well early (no real threat of an early elimination I believe), but thing might get a tad more complicated after that.
I can very well see him attacking Darius after Saladin's elimination, and suffer a deadly backstab by one of former war allies.
Conflict with Darius seems indeed unavoidable, and there lies his path to victory or to defeat: Darius will not be a pushover in this game.
By the way, if he does end up winning... while Domination seems the obvious choice, I bet he will induce much facepalming by going for Culture.
He can't plot at Pleased, which won't be an issue initially (religious conflict with Saladin, peaceweight difference with Darius), but may very well block him from further expansion in the later game. Plus, he'll have the early Holy Cities, and will get most of later ones through conquering the early tech leaders (Darius, possibly Willem).
So he could also get into a dominant position, and get beaten by a space launch while he's going for a late Culture win.
FTD chance: low, Win chance: better than average, Second place finish chance: average
Speaking of
Darius...
I bet that as the only high peaceweight leader in this game, with a warmongerer as a neighbour, and a rather lacklustre record, he's going to be a heavy favourite for FTD. Well, I don't see that happening here.
He might get into war with both Willem and Brennus, but each of them has looming threats on their other flank, so lots of opportunities to get out of the 1v2 situation. And with the land at his disposal, I don't see him collapsing to an early 1v1.
He'll fight Brennus, and one of them isn't going to make it to the end. Which one... is hard to say. Darius will have the early advantage, then be at a disadvantge while he's skipping Rifling and building infrastructure, then, if it's still a draw, get the upper hand again (better tech, better production one AL is reached).
But most likely, that conflict will be decided by who decides to join in, and on which side. Darius, with his peaceweight, seems likely to get the wrong straw here, but the religious situation might make thing more even than they look. Mehmed seems to me likely to often be the deciding actor (and factor) there.
Obviously, if he wins that conflict and survives, him winning by spaceship would then become a very real possibility... with another caveat though: Willem. Games where Darius does well are likely to be games where Willem does well too, and he guards that flank. But then, which comes first: Darius' spaceship, or Willem's culture?
Win chance: better than average, Second place finish:average.
Mehmed is the opposite of Brennus, and not just geographically.
While Brennus is bound to face early conflict, which he can then use to snowball, Mehmed's only early conflict will be with the barbarians. Sullla's said he had a backline at his disposal... but where's the food? Only barbs are going to settle that barren wasteland.
I suspect Mehmed will have a slow, sheltered start. Then he'll have to breakout. With "cannot plot at Pleased"... that'll probably mean an across-the-map attack (Darius: peaceweight, Brennus: religion). But with his crazy unit-build emphasis, if one AI can make that work, that's him.
(Then again, he could get lucky with JC for instance following a different religion, and get a closer to home expansion opportunity.)
So a Mehmed win would probably start with a late medieval/renaissance conquest at the other side of the world, for a late snowball that would se him to the stars. As for Brennus, and for same "Cannot Plot at Pleased" reason, he'll look like he's headed for Domination, but will probably get thwarted and have to settle for space instead.
Owing to a late blooming, there's also a decent chance he'll finish second behind an earlier bloomer.
Win chance: slightly better than average, Second place finish: better than avergae
Last,
Willem.
I'd say he has the best chance here, but not by much, and fraught with danger.
With his early Copper, I can see him going to war early, against JC or Saladin most likely. He'll be a tech leader, along with Darius. The both of them working together (at least not killing one another), would almost ensure that they share the top spots, but conflict at some point is pretty likely. Probably not a decisive conflict, but one that dangerously weakens them both.
Conflict with Caesar seems unavoidable, and that would usually spell doom for the Dutch leader, but with a caged Toku behind Caesar's back, I actually rather fancy Willem's chances here. Then with Saladin to the north, that's a second expansion opportunity. Willem doesn't need a lot of land to be competitive, and he could very well grab a lot here.
If he does, Willem winning by culture would be almost certain.
But it's not a slam-dunk by any measure.
For starter, he could fail to expand: Willem usually gets a few settlers very early, but then gets into wonder-building mode. He could end up severely boxed-in, with very little available land.
I can also see him running afoul of a stronger leader (Brennus for instance) at the time of danger for Dutch: when they're skipping Rifling to chase after all the "first-to" bonuses in that part of the tree, when their opponent, with 1/3rd the beakers, beelines Rifling...
Win chance:better than average, Second place finish: average to low
So...
Winner : Willem (30%)/Darius(20-25%)/Brennus(20-25%)/Mehmed(20-25%)
Second Place: Anyone but Toku/Saladin, really. Highest chance to come through would probably be a Willem/Darius ticket, safest bet Mehmed (as him coming second is compatible with any other winner, while a Darius/Brennus ticket is highly improbable at best).
FTD: Saladin > JC > Tokugawa
Victory condition: That one's easy. Domination. See, I'm fairly certain that it will not be Domination. It's going to be culture (Willem, Brennus), or Space (Darius, Mehmed). And I've been wrong every single time this season. So Domination seems a fair bet.
. That said my read is that Willem is going to pull the most Willem of all Willem moves, out-Willem himself one might say, and somehow manage to turn what should be an all but guaranteed victory into a spectacular disappointment. The only question is which leader will either slingshot Willem's land into a victory or get crazy enough ideas RE: Culture (the holy cities poison pill 
Sulla, those games are great fun for Civ4 fans..you really sparked new life here with the contest 
