Endurance

Endurance Training

Endurance is a SPECIAL stat that determines your character's physique and survivability. Increasing this stat increases your HP and the amount of AP drained from sprinting. Increasing this stat also allows to learn survival-related perks.

Toughness

This perk permanently increases your damage resistance. This is one of the "must-have" perks as it ensures that you won't die immediately before you can even hide or use that stimpak.

Lead Belly

This perk loses its usefulness as you increase your level and gain easy access to more than enough supplies of RadAways, Stimpaks, cooked meat, and clean Water. I would recommend not wasting a Skill Point here since cooked meat (hunting animals then using a Cooking Station) restores more HP without the radiation, and with occasional bonuses like temporary boost in Max AP, carrying capacity, etc. Also, you can just rest in mattresses (most locations have them) to restore HP, or drink clean water by building water pumps in your Workshops/ Friendly settlements.

Life Giver

This is a good perk early on since an extra boost of HP on a low-level character considerably increases his/her survival. At max rank, this perk also provides automatic HP regeneration. However, the regen effect will not be active in Combat since it seems to be working only when there are no enemies nearby.

Chem Resistant

This perk lessens your chances of getting addicted to chems. Chem Addiction is a negative effect that lowers your stats or resistance, depending on the type of chem you abused. This can only be removed by using specific Aid items that removes addiction or paying a doctor to cleanse it for you.

Since the game allows you to manufacture your own chems and mix them together for increased potency, spending two skill points here is a worthy investment. Chems like Psycho Jet which increases your damage output, damage resistance, and AP can be a life saver in life-or-death situations so being able to abuse them without getting addicted is a definite game-changer.

Aquaboy/ Aquagirl

This gives you more options when traveling and exploring. There are indeed some sunken locations in the game and having the ability to freely dive in them without having to worry about 10rad/sec amount of radiation and air is definitely a plus. Also, this gives you the chance to escape land-based enemies or just swim your way to new locations and avoid the danger along the main roads.

Rad Resistant

This perk increases your natural radiation resistance which can be further boosted by using Rad-X or equipping radiation resistant equipment. This will allow to explore highly radiated areas without immediately suffering the negative effects of radiation poisoning.

Adamantium Skeleton

This perk makes your limbs sturdier, making you less likely to go limp if you accidentally step on a mine or get hit by supermutant's bludgeon.

Cannibal

This perk gives you alternative ways of restoring your health, especially when you're off clearing off raider strongholds. However, doing this in front of your human companions may cause negative strains to your camarederie (remember, Dogmeat doesn't judge you!) Also, you'll be attacked by nearby NPCs if you decide to feast on one of their fellow citizens.

I wouldn't recommend this personally since the game already offers a lot of ways to restore your health without wasting Skill Points. Get this perk only if you're following a specific playstyle or preferred playthrough approach.

Ghoulish

This perk reverses the effect or radiation into healing. That said, this perk should not be purchased when you already invested Skill Points in Rad Resistant perk. The more you're exposed to radiation, the more HP you'll recover. If you stay in a highly radiated area, (or take a swim without the Aquaboy/Aquagirl perk) your HP will be constantly restored.

Solar Powered

This is the opposite of the Night Person perk since you'll get STR and END bonuses during daytime. In addition, higher ranks of this perk will enable natural radiation removal and HP restoration.

Images courtesy of Fallout Wikia.