I feel that legos is correct, and evolved much like the verb google (from the brand Google) has become. No one is going to say Lego bricks or blocks, they're going say legos.

So, I support the pluralized version and will probably continue with that, since it is about all I hear. To satiate the masses, I would distinguish with a capitalized version. Lego = brand and legos is pluralized version of where the branded item has evolved.