Hi,
The question is: what do you mean with "best team"?
If you want a good challenge on the best LLaMa spirit, just choose something from the Second or Third Divisions. This will guarantee you many hours of hard work to get them to the top Division and, who knows, Continental success. I still run a save in FM10 with Ipatinga, which was in the Second Division in 2009 (I guess they're in the Third Division now or worse). I'm in my forth season and we're finally on the top half of the First Division! TBH, we're on the second place after 2/3 of the season, but I expect this lucky streak to end anytime soon. Looking back how we started, I can tell you, it's great fun and proud!
Now, if you want to start in the First Division with a club already well established enough to challenge for the title and even succeed in the continent, then you have to choose one of the Big 13. The Big 13 are: Grêmio, Internacional, Atlético Paranaense, Corínthians, Palmeiras, São Paulo, Santos, Flamengo, Vasco, Fluminense, Botafogo, Atlético Mineiro and Cruzeiro. I believe they all have won the Brazilian First Divison title at least once (sometimes several times) and almost all of them have also won Copa Libertadores (the continental competition). I also believe that around 6 of them have also been World Club Champions once or twice (three times for São Paulo). They all have great history and have contributed with great players to world football. Name any great player that has been in the Brazilian National Team and most probably he'll have played or at least started his career in one of these clubs. So, no point to sit here and talk about the achievements of one or the other, just pick one. Perhaps, it should be fair to mention that the two clubs with the largest legions of fans are Flamengo, followed by Corínthians.
I started a save in FM12 with the team I support, Cruzeiro, since I'm from Minas Gerais State. This is one of the Big 13, which was runner-up in 2010 and almost got relegated this year! But this is the greatest fun about the Brazilian First Division: any of these 13 clubs can be either champion or relegated every year and there's no way you can tell it before the season starts! And every now and then, one of the other 7 "underdogs" will also challenge for the title and even win it! Now, let's hope I can do better with Cruzeiro in 2011 than the real club did...
Have fun!
Marconi