If the rules are the same it goes something like
Speed=Duration of Trip
Range=Max Distance Sub can travel
Survey=Ability to find items
Retrieval=% chance of gaining X amount of item.
Favor=Plays off like an HQ rate increase.
So in theory if you wanted the best odds of item retrieval you would want a focus on in order of importance I would say Retrieval>Favor>Survey. You can sacrifice Speed and Range as long as you can make the trip, while it might take longer to return the odds of reward quantity/rarity will increase if the other 3 stats are higher.
Sub wise we have the following.
-------------Survey, Retrieve, Speed, Range, Favor
S. Hull=-10/30/20/40/20
U. Hull=15/10/00/60/15
S. Stern=-30/20/60/30/15
U. Stern=15/00/30/40/25
S. Bow=50/40/10/-20/15
U. Bow=60/20/20/-15/10
S. Bridge=20/20/20/20/20
U. Bridge=25/05/25/30/30
(1)The Best Favor would be gained from doing S. Hull, U. Stern, S. Bow and U. Bridge=80/75/85/90/(90)
(2)Best Retrieval would be gained from doing S. Hull, S. Stern, S. Bow and S. Bridge=30/(110)/110/70/70
(3)Best Survey would be gained from U. Hull, U Stern, U. Bow and U. Bridge.=(115)/35/75/115/80
So currently the "best" Retrieval(2) has an extremely low Survey so odds of finding loot may be low but upon finding the quantity should be decent. Similar with survey(3), all into survey while you may have an easier time finding something it will be harder to obtain it.
I would honestly say that the best balance might be the Favor(1), it's a decent balance of stats but if you wanted to sacrifice Favor for Survey/Retrieve you could potentially just replace the U. Bridge with an S. Bridge which will give you 75/90/80/80/80 so even though you lose 5 Survey and 10 Favor you do gain 15 Retrieve which could be the different between bringing back 1-3 items.
Of course this is all just guesswork and my math might be off if I put the numbers in wrong but based on what we have so far I believe these are accurate setups that can be used in an attempt to getting better loot.