Got into the sport very late in life. I was introduced to it by World Cup 98 when I was like 10, and I one of the teams I liked playing as was Australia, with Viduka and Kewell up front. My favorite team was Belgium though, I was a kid and was reading an Indiana Jones book at the time and he was in the Belgian army, so I played as them in the game. Over the next few years I chose Leeds as my team since they had Viduka and Kewell up front and they were one of the few English teams that had players I knew about. I had my friend buy me a Leeds shirt when he was in England, and I still wear it today. In the World Cup 2002, Belgium was still my team (stayed up until 6.30 AM to watch them play Brazil, which was very late at that age for me). I didn't really root that much for the US during the cup but afterwards I realized that they were my country's team and that I had to stick with them through thick and thin.
After Leeds got relegated I couldn't watch or follow them anymore, especially after they went down to League One, so I kind of lost the connection with them. I went to the World Cup in 2006 and saw all the US games, which made me a diehard supporter. After that I started watching a lot more football, before, it would just be the occasional game. I still didn't really feel much of a connection to a pro team though.
When I lived in Argentina though I fell in love with their style of play, both the NT (although they sucked when I was there) and the professional teams. The first team I watched was Boca. I loved their style and Riquelme was great to watch. But I couldn't pick them as a team, not only are the Argentina's biggest team, literally about 60% of Argentines are for Boca (and the rest are for River)...I don't think there is any club in the world that has so much support from its local population. The clubs after Boca and River have very little support in comparison, and I haven't seen anything like it in any other leagues (except maybe in Portugal, but they have 3 big teams). I didn't want to be for River, either, since too many people were for them and then I would be involved in the whole Boca-River thing.
I still wanted to support a big team, though, obviously, and there are the other big 4 in Argentina, Estudiantes, Racing, Independiente, and San Lorenzo. Estudiantes is in La Plata, so that was a no. And San Lorenzo has Wal-Mart as their kit sponsor...that turned me off from them. That left Racing and Independiente. I watched Racing dodge an absolute bullet to not get relegated (during the playoff against Belgrano, the opposing player had beaten the keeper and was wide open in front of the goal and fell down, probably one of the worst moments I've seen in sports), and that kind of made me not like them: I really wanted to see one of the giants get relegated for the first time. I did see Independiente play a few times and liked the style, and I researched their history (and they have a great history, won the most Copa Libertadores) and decided they were my team. I've watched most of their games since, though it depends on circumstances. It's really hard for me to watch their league games now because of the time zone difference, and there is no way to download their games and watch them later (you used to be able to with rojadirecta, and there is an Argentine site, but they never have Independiente games for some reason, and in the case of the Argentine site, if they do it's usually like two weeks later). I've bought two of their shirts and I consider myself a fan, though I guess I'm not a "real" one.
In the MLS I guess I like the Seattle Sounders because I lived there when I was a kid, but I may end up moving somewhere with a team and don't want to get too attached to them yet.
I really admire Arsenal for their fiscal policy and youth and football philosophy...I love the fact that they buy cheap, young players, develop them into greats, and sell some of them for very high prices. They also are the only team in the Prem to play attractive football. So right now, I am a really strong neutral for them, and think it would be great for the game if they started winning trophies.
As for Barca, I'm in awe of them for their youth and football philosophy. The fact that they have 8 youth team players in their starting 11 is incredible, as is the fact that great players can't even play well with them because they don't have Barca DNA (even Villa has been outperformed by Pedro this season) shows the psychic energy this team has. On no other team do you have that type of integration; on any other team in the world you can expect good players to settle in, but for Barca, it takes years to think on the same page as the other players. They play the most beautiful football I have ever seen, and when they are on their day it is absolutely unreal. I really hope they win the Champions League so they can be undeniably remembered as an historic team. They are already, just by the virtue of their performances over the past few seasons, but I want them to get the results too so that no one can deny it.
Unfortunately I have no connection to either club and don't want to be a glory-hunter like all of those American ManU fans I see everywhere. And if/when either one of those clubs abandons their philosophy, I would stop wanting to see them succeed. I would like to adopt a Spanish team, since Spanish football is the only European football I really like, but I've never been to Spain and don't know how to pick one...and even if I did, it would feel artificial. If I ever move to Spain though I'll definitely support the local team.