I clearly like Vas over Gibson but yes Very tough situation man.

1) keeping Vas as u have the Bishop/Vas combo (Vas will get more games this year) until Bishop gets moved. Then u have 3 clear #1s.
Problem? U only have Andersen who won't give u much this year(not to mention injury prone). Worse scenario Bishop gets moved to a bad team. Yikes.

2) Gibson is a #1 goalie but as mentioned he is inj prone. You also have to consider the Bernier factor. He's got something to prove. Playing for a contract. If he regains his ability on a good team...... Look out! He could steal some serious games.
Either way has issues.
Verdict:
Win now: Gibson
Wait: Vas. But if u want half a chance of repeating this year u'll need to upgrade on Andersen.