i voted bilbao. purely because the board restricts the squad to contain only players of basque descent, which essentially means anyone born within a stones throw of the stadium. Meaning, aside from the odd player they may pick up for peanuts here and there, they rely soley on the products of their academy.
even with this policy they have managed to stay in spains top flight for a number of years.
recent graduates that have been successful are:
etxeberria
yeste
iraola
llorente
susaeta
iker munian (great prospect)
ustaritz
in terms of talent you cant really argue with barca. xavi, iniesta, messi, pedro, puyol, bojan, valdes, pique (via united) fabregas, dos santos