The 1991 Series between the Braves and Twins was a classic as was the 2001 Series between the Yankees and Diamondbacks.
I would say Game 6 2011 World Series AL champ Texas Rangers vs St. Louis Cardinals. At the end of the 11th inning, David Freese's homer was one of the most powerful events in the past 50 years of baseball. A nail-biting classic, however the next day, the Cardinals claimed their 11th title in 2011.
Another favorite would be the Game 6 of the 2009 WS. The Yankees finished the Phillies off for good, and they won the title for the city, the new stadium, and for Mr. Steinbrenner.
Another would be the 2005 WS, the Chicago gained respect not only from the Chicago Cubs and the rest of the MLB, but the nation. They represented the American League so beautifully, probably the second best American League representatives next to the Tampa Bay Rays in that '08 thriller.
The 2011 World Series. The Cardinals won it, it was exciting all the way through, went 7 games, and unlike the 2006 win, I wasn't in college and had time to watch every game (thought I did see most of the 2006 Series, I missed a little bit as it was right around midterms).
My favorite would also be the first though i do have flashies from time to time of how dominate Bob Gibson was in 1968. 1969 a 9 year old wishing on those amazing Mets. Hey ump the ball hit Cleon Jones the manager Gil Hodges said look at the ball. The "shoe shine" take your base sparked a rally. The crossing guards at school wouldn't let you cross unless you said the Mets would win. Day games then and our teacher an orioles fan let us watch them in class.
1991 Twins beat the Braves in seven games. Final game was a 10 inning shutout by Jack Morris and Minnesota won with a walkoff single in the bottom of the 10th.
I'm torn as a Rangers fan. In 2010, we just get dominated. In 2011, we were competitive, but it was just too heartbreaking really to call it my favorite World Series. I will never forgive David Freese for his actions.