Naturally I can only name those matches in which I have played.
ENSL2 Levitacus vs. storm.ns 3-1
http://www.ensl.org/matches/707
It was really disappointed season for Levitacus, especially because Levitacus was rated one the biggest rivals to Storm at start of the season. Inactivity and loss of key players had hit hard on Levitacus, though, end of season Levitacus start to become active again and in the very last match they would face storm. Only chance to reach the finals would be 4-0 win over storm.
Match illustrated more about character than teamwork or great personal skill. It was good even match and Levitacus shocked scene by winning first 3 rounds deservedly. In final round, map was eclipse and Levitacus would be play as aliens. On paper this round should be the easiest one for Levitacus and Levitacus had also massive momentum advantage at this point. However, Scale's early lerk did get stuck to infamous wall next to eclipse hive and for some reason stuck-command wasn't familiar in ENSL back then. Early lerk was vital part of the alien game and Scale was one the best lerks back then. To be honest, storm could have won it anyway but game was anything but over at that point. Week after the match storm would dominate Insane in finals.
ENSL5 Levitacus vs. Testicules (Insane) 2-2
http://www.ensl.org/matches/2166
It's crime against humanity, that there aren't demo from this match. Both Levitacus and Testicules were active that time and they showed spectacle of teamwork. Both teams were famous from their skulk teamwork. Marine pressure teams were group camped before marines reached alien rts. This is something which has fallen to oblivion in 3.2. It actually was the last match of real teamwork. My computer blew up, and rest of the season was joke to Levitacus. Testicules also struggled with inactivity and finally folded.
ENSL6 Finals Saunamen vs 9L 3-3
Don't get me wrong, it wasn't the greatest game due inactivity of both teams, though it wasn't bad either. Inactivity made possibly for great individual performances. Season 6 was definitely best season from my personal point of view.
Above all, this game was one the biggest milestone of NS. After this game both clans folded and almost every player from both clans quit NS. Before this, in top clans majority of players had to have high level playing experience and often every player had years of experience. Suddenly, top teams contained only one or two players which had that needed experience, which they could pass on to next generation. It didn't surprise me that teamwork and tactical knowledge went downhill. This hit me hard, when DU won ENSL7, how much skill level had dropped down.