Second Principles: New Life - Help the Young or Live to be Old? (Patreon)

Back in 1.31 (pre-second Kickstarter) there was absolutely no choice between Protect the Young (PtY) and Survival of the Fittest (SotF).  SotF was an awful experience that killed your settlement by attrition over time, while PtY allowed you to not get wiped out through random events and timeline punishment.  It was a no-brainer of the highest order.

1.5's version of the Core Game revised SotF with several upgrades, but left PtF intact in its original form.  

Milestone Event

SotF's milestone event is 50% chance of +1 strength +2 insanity skip next hunt for the parents vs. 50% chance of +2 courage, Tough and one random disorder for the child.  PtY is also a 50/50 split, but it is +2 Survival, +1 Evasion for the parents vs. +2 Understanding and Strategist for the Child.

It's clear that the best result is 2 survivors with +2 evasion and the second best one is a strategist with +1 Evasion. So overall PtY wins this. However you need to remember that SotF also gives +1 Strength and +1 Evasion to everyone while PtY does not have any equivalent passive bonus. 

Winner: Protect the Young

Passive Bonus

Protect the Young brings roll twice and pick the result you want, reducing the chances of death and increasing the chances of getting the best results.  However, Survival of the Fittest brings two passive bonuses and one drawback.  SotF gives us +1 Strength and +1 Evasion to all survivors, plus an increase to the survival limit, at the cost of having to roll twice and pick the worst result on the intimacy table.  

This would appear to be close between the two, but you have to consider the sheer power boost that SotF gives in the early game.  +1 Evasion and +1 Strength is HUGE and combined with the +1 Survival Limit you're probably going to be in a position where your survivors rarely die.  (You can hit in excess of 5 evasion with little effort early on if you want).  

The 'cost' of this is that your population should on average dwindle in size because children (and parents) are less likely to survive. However that is negated by the Activated Bonus of SotF, it's lifetime reroll.

Winner: Survival of the Fittest

Activated Bonus

This one is very one sided; Survival of the Fittest has the once per lifetime dice roll ability, which is immensely powerful. Protect the Young has no activated ability at all. 

I could just stop there, but I think it's worth explaining why the reroll is so powerful.  Adam has clarified that this reroll can be used by any survivor 'present' when a roll is made in order to reroll.  It can be done multiple times, but you cannot take an earlier result if you choose

Winner: Survival of the Fittest, because when there is only one candidate, there is only one choice.

Triggered Events

This one isn't even close, there are so many hunt events that have extra bonuses or damage mitigation if you have SotF that it's not even funny.  It's like the entire hunt phase was restructured around rewarding SotF.  So I'm not going to go into it in details, let's just call the winner and move on.

Winner: Survival of the Fittest

Summary:

Survival of the Fittest pretty much trumps Protect the Young in almost every single category.  Now there would be some contest between PtY and SotF overall, except Face Painting is a thing.

Because you can activate Founder's Eye over and over in order to gain +X onto ALL intimacy rolls you make and you can stack this with things that let you get lots of endeavors (Graves + Heart Flute, Collective Toil, Tinkers) or Intimacy rolls (Love Juice, Matchmaker) you can very easily be patient and create years where the population spikes.

Also the ability to reroll bad intimacy rolls with SotF makes most of PtY's benefits meaningless. So like many things in 1.5 which were buffed, SotF is far more powerful than it the other option.  However, there is a caveat to this - in People of the Stars the answer is not so simple or clear because of the changes to the intimacy table. 

Overall Winner: Survival of the Fittest by a very long margin.