I like watching how different philosophies clash with each other, how they react to difficult situations, etc. I want to see how things work out in the end. This is engaging. Conflict is better than no conflict, because it both helps you better define your views, and changes them over time.
I always want a sense of progress in my character's storyline and other characters' storylines. Sometimes it's as simple as achievement, e.g. getting inducted, getting your promotions/leadership, or it can be new RP angles, new contacts, change in character. It's one of the reasons I like to play to age-death -- I want to see the whole story.
Immteraction is only as valuable to me as much it allows me to discover about an Imm's character, or my own. Imms generally have well thought out philosophies, so it's interesting to "put them to the test". They also facilitate interaction with other PCs.
PK... PK can be engaging, but it can also be a chore. It all depends on the situation.