when i chose my skills i was on ground did not see much/any difference in weapon attack power after picking it as for the health it is 20% of your max every 60 seconds. between 100 to 120 health regen but in battle you have hypos any healing kits provide the extra health is 60 seconds away. how long can you stay alive on low health in battle? if only a few seconds go for the extra gun damage however small. example tactial officers gun boost reason your life is often short give a bigger shot while alive you may be faster and kill before killed.
science officers gun boost if a medic kit and large hypos isnt enough to keep you alive buddy nothing will your damage is the smallest healing greatest might as well try having a better bang from your weapon.
engineers you can stay alive and do good damage but mostly shield alive and hypos you'd be best with the health keeps your health going up while your shield healing abilitys keep your shield from failing keeping you alive even longer.