1. MM - Indisputable. Been a F2P power house for so many years when it counted, and they were really good in P2P as well. Foe made MM run for their money regularly though (clans like Epidemic and Eop did the same now and then, but not on the same scale as Foe). It's no wonder MM had the biggest and most active community (probably still bigger than most pure clans).
2. Foe - Foe has had its ups and downs, but mainly ups. In the years following the first era, Foe were for the majority pretty much ahead of Eop and Fi and Foe was the only clan to give MM proper fights and challenges on the long run.
3-4. Eop/Fi - When pure clanning started Fi was the most dominate clan for a really long period. Eop did beat Fi a few times during that first era. Since that first era Eop has been the more dominant and active clan of the two (based on the period after 2009). Both clans have had some slumps, but they always pulled through. So I guess it's safe to say #3 goes to Eop while #4 goes to Fi.
5-7. TLP/Epidemic/CP - TLP was a very stable P2P powerhouse that had amazing and dominant periods challenging the top 2 clans. In F2P they were very good, but usually lacked the numbers. A few years ago they were one of the strongest powerhouses during the 39 def era. I put Epidemic on the list because Epidemic accomplished what no other clan has ever accomplished in less than 1,5 year in the hardest and most active pure clanning era ever; dethrone the indusputable #1 clan MM in F2P with inferior accounts. Epidemic had gained their goal of taking #1 F2P by surprise. Epidemic is only on this list because of that feat. Epidemic lacked the P2P skills and numbers to be a serious contender vs clans like MM, Foe and TLP (the majority of our members hated P2P). I put CP on the list due to their long history and because they've had their periods of dominating the F2P scene. This was however during weaker clanning era's when every +1 was pretty much auto-accepted (eldercontracts anyone?).