You can choose to leave negative or positive words, I've thoroughly enjoyed fighting all of the rivals I've had at Calamity and Control over the last six years so mine will be strongly positive. Any flaming/trolling/trash-talking was all in the spirit of the rivalry. Just a bit of banter boys.
IR - First real rival in 2007 for CY, and then again for CT in 2011. Gave us really fun fights in the wilderness and the rivalry had a great atmosphere. Gave us most of our mini-wars in 2007 with CY and always had a bit of banter with Hotkeying in 2011.
TGG - Was more of a friendship than a rivalry, had a couple full-out wars but they were all followed with respectful spamming at edgeville from each clan. I've always got time for TGG leaders because of the enjoyment they provided to the CY members by having events with us.
DV - Provided both CY and FS with the only P2P-based rivalry I've ever felt passionate about. Provided us with some amazing fights and a great full-out war to end it on, DV probably just edged the P2P side but we managed to make up for it in the F2P server.
UT - Were the first big rivals of Calamity in 2009, they didn't give us much in the wilderness but they were good enough to accept a full-out war which we all enjoyed. Massive respect to the leadership for giving us a good 70v70 fight.
CP - Were always around to give my boys a fight with CY in 2009 and then again with CT in 2011. A little disappointed that we could never get a full-out war with you guys but we had plenty of wilderness and bounty hunter fights to make up for it. Always admired your strength in matched-opts fights.
Z - Without you guys we wouldn't have had even half the fun that we did in Control. You provided us that exciting weekend-by-weekend rivalry and kept your pulls up to ours so that fights were never boring. We were actually really sad when you closed because we didn't get a many close fights as we used to.
FI - Provided us with most of our action towards the end of CT, were nice enough to have a full-out war with us when no other clan would give us one. The outcome didn't really matter for us, was just a great thrill during the week and on the day. One of the best moments of the Control lifespan for me and it wouldn't have happened without you.
There are many other that Calamity, Control and even Fearless had 'rivalries' with but they are not as significant as the ones listed above.