I don't want to read any other posts because I'll fall into someone else's thought stream on this...
You said, 'human emotion' linking a 'powerful feeling' that, as I understand this question, has to stand either separate or above other animal responses, i.e. what we understand--limited, to be sure--that animals feel as emotion; or put another way, if an animal can feel it, do I rule out those which I can as well--thinking as I go along--that if my cat, Zooker feels, for instance, 'fear' and reacts... and so do I--feel fear, and react, then I cross that off my list as either being 'animal instinct', a part of the human makeup that is animal in nature, or as involving thought--to separate me (in my own mind, as a human?) from lower animals, and therefore no longer simply what you asked:
What is the most powerful human emotion?
I'm going to cross off all those that animals and my animal self--the lower self--feel (fear is out); need in an animal we often call love or lust or some other name to indicate our superiority, but I don't see it that way, and I'm answering 'as' one human being about what I take to be 'human emotion', so...
Demote
emote
Human not animal or only animal:
Highest has to be:
Compassion: It is deeper, it is higher, it comes from what I think of as spiritual evolution; when we lose it, we are temporarily or permanently (if that is possible) devolved, back to animal 'only'; back to pure reaction and instinct (for those who see animals as incapable of reasoning):
Compassion, for me, is the most powerful 'human' emotion.
No other animal that I am aware of--and I don't play 'Let's Google it and use a lot of razzle-dazzle verbiage to 'cite')--is capable of feeling (always presupposes, this 'compassion' does) that I have reasoned to some extent about whoever (solo person) or those (entire group) I feel sorry for (not pity, not 'looking down upon') going through a certain experience, having a particular rough stretch:
The examples don't matter as much as this:
Genuine compassion must be rooted in self-love.
I can only love another (I am talking about something other than 'attraction'; other than lust; other than 'need' of a child, at a child level...); I can only feel compassion, which is a component of, or a particular feeling that grows out of the kind of awareness of my own self as mattering in a divine sense, and by divine, I mean:
Not utilitarian; not 'what is in it for me'; not some abstract programming I can spit out to enhance a false sense of my own worth as something like 'a good person...', you know, 'a good person feels compassion; I can't bear not to be seen as a good person, so I feel compassion, I say I do!.'
No: Actual compassion means I have to have an honest sense, to the extent possible, of when I am not; how I am not feeling compassionate:
I may or I may not have the 'authority' in a particular situation to alleviate someone's suffering 'based on the compassion I feel' but whether I do or do not have this authority, I feel a kinship, a caring likened to what I feel for myself...
It isn't something most human beings feel often, deeply--or perhaps even recognize as having a divine source, that 'being made in God's image' aspect, and again, to be clear, I am not talking 'religion' in the debased sense, you know, I go to church; I sing hymns with 'love lyrics' in them, et cetera.
No.
I see someone suffering = I care and as it was written of Jesus (and I'm sure there are other examples, similar enough), 'He groaned in his spirit.'
In his spirit.
Not an animal aspect to this compassion as I am defining, working out what that word means to me, and it is most powerful of all precisely because it comes from The Ground of Being that links us all, and to the extent that I feel that, I am in touch, for no matter how short a time, with that Ground; with my own and other's Being (not doing); with Being.
~ Carolyn