I would say the three best concerts I have ever been to were Black Sabbath, Lynyrd Skynyrd and Van Halen (some may have called them Van Hagar at the time).
A concert that I did not expect to enjoy much that really turned out to surprise the heck out of me and was really good was Elton John. My girlfriend at the time wanted to go and I went just because she wanted to and thought I wouldn’t like it but he put on such a fantastic performance that I was very impressed even though I am not a big fan of Elton John.
I would say the concerts that were the worst I have ever been to was a Rod Stewart concert, it was SO BORING that I could hardly stay awake and then as much as I love their studio work The Allman Brothers bored me, and that was each of the three times I saw them. It is like in almost every song they go into a 20-minute jam that sounds so much like the last jam that it is like you keep hearing the same song over and over again and at times their jams are so long that you can forget what song they were playing.
They are really talented and as I said I love their studio work they just aren’t much fun to see live. Many bands are exciting to watch let alone listen to but The Allman Brothers Band all seemed to be really bored up on stage and did not excite the crowd.
One of the times I went to see them I was right up front and had a great view of Greg Allman and even though I had front row seats I brought some binoculars because I like to zoom in on the finger work of lead guitarists as much as I can but I found myself watching Greg Allman much of the time. He looked so totally bored that it was a real downer.
He would sit in the middle of his semicircle of keyboards and when not playing just stare with a blank look on his face. At times he would light a cigarette and stare off backstage and other times he would walk off stage and then when it came time to play a little he would walk back to his keyboards and lean over, not even sitting down sit times, and play a little and then walk off stage again like something was more interesting back there than it was to him to be in front of a crowd.
The best moment I ever had at a concert was the last time I saw Black Sabbath on one of their reunion tours. I had second row seats that were dead center right in front of Ozzy. As many of you most likely know Ozzy loves to throw buckets of water on the crowd and to spray them with something like a super soaker that is attached to a hose. He nailed me with a bucket of water and later I managed to get his attention by holding out my fist and showing him a skull ring I wear.
It is the same skuul ring that Keith Richards wears, bought at the same place, The Great Frog in Loondon, and I bought it from the same sales lady that sold Keith his. Ozzy has one and Alice Cooper has one (you can see his in the movie "Wayne’s World" when Alice holds out his hand for Wayne and Garth to kiss after they kneel before him saying "we’re not worthy, we’re not worthy.") Billy Idol has the same ring and you can see it in the Adam Sandler movie "The Wedding Singer" when near the end Billy is sitting on a plane seat with his arm draped over the back talking to "Robbie," Adam Sandler." You can see Keith Richard’s ring in the third "Pirates of the Caribbean" flick when he is looking through the pirates code.
Anyway I think Ozzy spotted it and recognized it because he got a really big grin on his face and picked up his hose and hit me right in the face with the spray. He sprayed my face so long I was starting to cough and choke and I held up my hand to block the spray to get a breath of air. Ozzy lowered it down to my chest and just stared at me grinning really big and gave me a moment to catch my breath and then raised it up and plastered me right in the face again. I think it must have been shown on the big screens because the crowd went wild.
What made it so great for me is because I had enjoyed Black Sabbath and Ozzy so many times over the years and for those few moments it looked like Ozzy was really enjoying himself and to me that was like I was in some small way paying him back for all I had gotten from him and the others over the years. Also in a very small way since the crowd reacted like it did making me figure it was being shown on the big screens it was almost like being a minor part of the show for everyone that might so that made it really fun too.
, but..ah! good times 
