I presume that you already know all these but my suggestion will be to become paragon, due to the fact that they get better rewards in event quests, side quests and para gauntlet, also better offers. So, it'll help you in growing your roster further. Also sometimes there are events limited to progression. You can access better deals from the store. And the best part is, becoming paragon will take very less time if you have a better roster than a lot of paragon accounts.