bluejaysplus.com has just been "relaunched" and carries a lot of content.
if you can handle the snark, andrewstoeten.com hits and misses but updates regularly.
bluejayhunter.com does some good stuff, but updates are sporadic.
fangraphs for everything else
this is the best sites for breaking news and near the top for (some) of the comments.
EDIT: also Ben Nicholson-Smith, Shi Davidi, and Tao of Stieb all located at Sportnset.ca. Ben and Shi are doing a lot of feature pieces and long reads this season.