Not sure if you're still open for conversion for pro soccer teams but let me throw out my favorite club and why.
Reasons to cheer for the Arsenal (English Premier League-EPL), in no particular order:
1. Their fans are proudly(and ironically) called 'Gooners" that has a Philly pheel to it
2. They have qualified for the Champions league beginning in 2005-present, meaning they have placed in the top 4 of the EPL for the past 9 years. Hard to do.
3. They do not "buy" their teams in the same way as Chelsea and Manchester City. European/Champions league clubs are obligated to follow the football financial fair play regulations--many clubs, such as Chelsea, Manchester City, Paris St-Germaine, and others (especially those run by billionaires) choose to ignore the rules and circumvent the system. Arsenal follows the rules and have structured their team to succeed under the regulations.
4. The Chelsea poster compared them to the 49ers and I would compare Arsenal to the Spurs. They have an old school coach who follows the system, prefers international players, they have unselfish stars (Mesut Ozil, Aaron Ramsey, and Theo Walcott).
5. They got dudes named Per Mertesacker, Nacho Monreal, and Yaya Sanogo, c'mon
6. Their best team went undefeated in the EPL, 49 straight, and are called the "Invincibles"
7. Their international players play for England, France and Germany.
Germans: Mesut Ozil, Luckas Podolski, Per Mertesacker
French: Olivier Giroud, Laurent Koscielny
English: Jack Wilshere, Theo Walcott (injured), Alex Oxlade-Chamberlin
The players above are currently involved in the World Cup but they have more international players.
8. They are consistently on a favorable times in America because of their popularity--don't have to order special cable channels or wake up ridiculously early to watch.
9. The Austin Gooners have a standing watch party in the "attic" of the Tavern.
10. They play a pretty, aggressive brand of soccer and do not "park the bus" and play counter-attack football that most Americans find distasteful. They lose some games this way but they always play to score and attack.
Links to some of their best goals this year:
Arsenal is the team in red:
http://youtu.be/8ZNFxLO4fEc
http://youtu.be/Qk8WOmh26E8
*apologize for not directly linking--not sure how to do multiple links.