Nick Chavez @nickchavezMLS
Dave Martinez @empireofsoccer
They have been good on pending trades/news, etc.
The national writers like Grant Wahl are good follows, they have been covering us recently.
Taylor Twellman and Alexi Lalas are great for general MLS news.
As for the players, they are hit or miss. Some use it as a marketing account, (unfollow) or just post family things. David Villa just puts pics of his family or things in spanish. I can' find McNamaras twitter, that would be a must follow