i'm going with kissing. most of us don't close our eyes and pretend we're kissing someone else. there's a reason why hookers don't kiss their johns...
Context is all, but in general I say kissing.
I knew a woman who considered performing oral on her an extremely intimate act, and you had to build a lot of trust before she would let you. Nothing else off limits, just oral. I gotta admit, it made the act very special when I was finally allowed, and was actually kind of moving.
being with someone that values everything that you are
Intimacy has nothing to do with any physical act, it's a "knowing." Knowing so well you can have a conversation without saying a word.
Since we are limiting it to just those sexual acts, I have to say kissing just as I orgasm from vaginal intercourse.
Or with a woman, kissing while we orgasm together with our fingers.
During the hug when she whisper in my ear.... touch of her lips on my neck....