So far I find toughness, extra damage for X weapon type (I use non auto rifles myself) because they give damage and defense bonuses without the need for resource gathering. The barter perk seems to give a nice 20% discount on prices and of course lockpicking and hacking. After I get those I move on to the crafting perks like armorer and gun nut.
Which perks do you find invaluable in beginning of the game?