The one I can remember that was the most profound and the most blissful came sometime after kundalini activated the thousand petaled lotus in my crown chakra. Energy in my body slowly built up to a point where it was filling literally every part of me. I know that probably sounds redundant because energy is supposedly anywhere and everywhere, but it was the sheer mass of this energy and the brightness of it that I could see that was just pure ecstasy. And it just kept building and building. The structure was unique and symmetrical, the brightness of it was delightful and pure. It kept building until I was hospitalized and I haven't been able to experience that ever since, except in certain states of mind where I can reach just a small piece of it.
I called it the AVATAR state and likened it to what some yogis and sadhus and such call the light body. At the time I couldn't imagine living without it...