I think you have to keep both personally, as you mentioned goaltending is typically the most sought after position in a dynasty/keepers, especially as the league progresses. If possible try to bundle one of them with Morin/Kreider for an upgrade keeper. I would look to the Neuvirth or Leighton/Boucher owners first, then whoever has the least goaltending depth. I consider both Bob/Varly to be top end goalie prospects on great teams, so you should get a very considerable return in a trade.