If you are going melee, survival is best. I often go with the cowboy perk and shotgun surgeon along with hand loader and jury rigging (far more useful than people say.) Making weapon repair kits is super useful, because the ingredients are littered in ruins. Also, plasma ignores a ton of DT and while spends a ton of cells, is probably one of the hardest hitting weapons in the game. Not only can you get the vigilant recycler perk, which increases the amount of juice you get from spent cells, but you can also turn fission batteries into Energy Cells, and combine cells into more powerful cells. If you are using Energy Weapons, science is a must-have.
Survival, repair, explosives and science make useless junk useful: I highly recommend them all, but I follow this order. Also great for making food and misc items. Not only do you get a ton of really good healing items (super useful on survival mode as well as on normal mode), but you get tons of poisons, healing items, and kick-ass chems like rushing water, the weapon binding ritual, battle brew, and a ton of antidotes to poisons. IMO, survival is one of the most useful skills.
