The best ever was Elton John, the year I am guessing was about 1990. I went with my best friend who was in the early stages of full blown Aids. Sadly, the protease drugs did nothing to help keep his disease at bay, and he was slowly dying. Very sad for me to remember.
Anyway, we went to this Elton John concert expecting the worst -- it was raining pretty hard and it was at an outdoor pavillion, and we had lawn seats. We decided to make the best of it, and bought some hefty trash bags before we went in, and just put those over our heads. I'll never forget that concert, it was beyond electrifying. His version of Funeral for A Friend (so poignant considering who I was there with) was the best song I have ever heard anyone perform, anytime, anywhere.
I treasure the memories I have of that concert. Sometimes I start to forget bits of it, so I have to make myself remember. Its my last and final link to my friend.