I see that some people are having arguments about regions and whatnot. I will tell you right now, I just spent about 15 minutes researching the top 3 clans from the 5 different regions, and now I will compose a list of each region followed by a list of the regions combined. This list was based mainly on clan battle records. I'm sure the list may change if clans were to battle each other again, but for now this is what I came up with.
US
1) Forgotten - based on track record, they have the most wins and have a great leader. While they did lose a few members, they are a very real challenge and until Rebels or Titans faces them, they are #1
2) Titans - I want to show no bias in this post, but considering the other clans I researched, I believe that Titans are an easy #3, and also pose a challenge for the other US clans. We have very dedicated members who all know how to work as a team, and our officers and elites can stand in as leaders during scrimmages.
3) Rebels - One of (perhaps, the) oldest clan existing, Rebels have gone through many changes since their beginning. They have a large roster with enough players to bring all skills to the table. They are a regularly challenging clan when my clan scrimmages them, and I hope that one day they can also achieve the number 1 spot like so long ago.
Notable mentions for US - Blamphs - A resurrection of a previous #1 clan, the Blamphs have already received a stacked roster with some of the best players, new and old. Before the Blamphs can be compared, they must find out how to work as a team and then they can scrimmage and battle the best of the best.
Aviate - Aviate is a very organized and well managed clan, their leader was unheard of when he started the clan, but when everyone saw his experience and knew how well he could make Aviate work, the clan started booming. Similarly to Blamphs, they have yet to face upper-tier clans and thus, I can not compare them to the top 3. (Disbanded)
EU
1) EU Rebels - a similar case to Forgotten, they have yet to lose a clan battle and have defeated many challenging clans. With members from all around Europe, they get to know each other very well and can work great as a team, with each members individual pvp skill an asset.
2) Hellfire - what can I say, Builda_Brett is a great leader. He led his team to beat one of the best EU clans in history, and they show that they deserved all their wins. I place them at second, mainly because EU Rebels has defeated them. I feel like Hellfire would be a challenge for clans in other regions as well.
3) Nitride - You may think, BLAZER WHAT ARE YOU DOING, but based on track record, the Squad is not only one of the longest running clans as well, but they hold their members to a high standard, not taking anyone with less than 300 wins. ExoticPenguin is actually a very smart and proficient leader who knows how to manage a clan, after all, they've been around for almost a year!
Notable mentions for EU - Nitride - Nitride also poses a challenge for EU clans, but because they have not faced any of the clans mentioned above, there is no way to compare them.
AS
1) AS Rebels - the only true AS clan in my eyes, there are none who can stand to the AS Rebels. They were formerly known as Akatsuki, a group of skilled Asian players who actually existed before the AS division was created. Because AS is actually one of the least played divisions, there are no other clans that I believe are worth putting on the list.
CA
1) CA Titans - Again, because there are so few clans in this region, there is no one to compare the CA Titans to. They have hardly even fought any battles because there are no CA clans to fight! Once again, the Titans can and will bring a challenge to all opponents.
AU
1) Phoenix - Phoenix has proven themselves to be one of the best clans worldwide. formerly known as AU Forgotten (or AU Rebels, oh gosh I can't remember), they were found good enough by one of the top US clans to be worth naming their counterpart. Although darkrai is a leader who's value is up to discussion, I believe he works hard to manage his clan, but still have fun while he does it, and this shows in their battle record, where similar to EU Rebels, they have not lost a single battle.
2) Apex - one of the oldest AU clans, they have a large number of clan battles, only one of which they have lost, which they also rematched (Blitz) and won. flok, croe, and oma take great care of this clan, and work hard to pose a challenge to their rivals, like Phoenix.
3) NuggetZ - yet again, the Nuggetz are back and ready to battle, after taking a short break, Juzzyy returned to make the Nuggetz yet again a feared clan in the AU division. While they haven't faced the clans above, they have beaten many clans below, earning the #3 spot.
*Note - this is the part of the thread that people will have disagreements on. I have spent about 20 minutes typing this up and doing research on the clans, and if anyone else is willing to do what I have done and have a differing opinion, I'd actually be glad, we can let everyone know that opinions do differ, especially on this topic, where every player from different regions will have bias.
World - This list will be a top 5, to incorporate the #1 clan from every region.
1) Forgotten - US MCSG clans will always be the most popular region, mainly because US and EU are the dominant regions in MCSG as a whole. This also means that EU and US clans will be the most dominant region. When it comes to hard work and determination, the current members of Forgotten are some of the most skilled players in MCSG worldwide. Many of their members are old-timers, beta players or pre-MCSGv2 players. They know how the game works as a whole, and are experienced PvPers. The Forgotten clan has had several drawbacks, including losing several members to other games, but Forgotten was always still a challenge. There's a reason why, as soon as they came back, they were ranked once again among the top 3. They have (to my knowledge) the longest winning streak in clan battles (EU Forgotten held this title, but they are no longer). Soulv2 is a big key to their success, he is one of the best strategic leaders and players in the game itself. I believe that, given time, other clans may take over the #1 spot, but there will always be a place in MCSG history for Forgotten, the current best clan worldwide.
2) EU Rebels - What can I say, EU is tied with US in the MCSG dominance spectrum. I think that, given time, EU Rebles would definitely be able to take the #1 spot. However, there are ways to compare the EU Rebels to Forgotten to show why Forgotten is better. Every Forgotten member has been around for a long time. They are all individually skilled as one of the best in the world. Soul is one of the best leaders around. xExtract has been named by more than a couple people as the best PvPer in MCSG as of now. I think that if EU Rebels worked a little bit more on having every player have the ability to take over as a sort of squadron-leader in the case that any other players were killed in a battle (for example), then they would have no problem taking the #1 spot.
3) Phoenix - As the #1 AU clan, the AU region is the first that I can say, there is a real challenge to be had. In CA, you have lots of good challengers in the form of individual players, but not so much in clans. In AU, the individual players are a challenge, along with the clans they belong to. Phoenix has proven themselves to be the best in AU, but I think that even with darkrai's skill in leadership, they would not do well against the top 2 clans.
4) AS Rebels - I have a firm belief that the AS division is one of the easier divisions to play on, especially if you are skilled. I know some people may not want to admit it, but there are not nearly as many good players on AS as, for example, EU. This means that a group of AS players (who are very skilled) would have nearly no challenge. The AS Rebels have not had a real challenge in a while, and this is why I am putting them at the #4 spot. I really do wish that having clans battle across regions was an easy thing, but this will probably never be the case.
5) CA Titans - Because they were the only CA clan, I did put them as #1. But comparing to the skills of other region's rosters, CA Titans would prove a minimal match for the rest of the world.
In conclusion, I'd like for other around the globe to share their opinions on my opinions. If possible, refrain from flame on my thread. I want to be able to make adjustments to this thread if a lot of people believe that some things should be changed, but I'd very much enjoy seeing others learn about the other regions and/or talk about their own.