Radiohead, South Park, Oxford 2001 has to be the stand out concert for me so far. The first time they played the Kid A/Amnesiac tracks alongside The Bends/OK Computer stuff. Supergrass and Beck were also on the same band list.
Idles at Concorde 2 a couple of years ago was also a great night of live music.
I went to that Idles gig. Superb.
I turned down tickets to Radiohead (I was living in Oxford at the time), to go to a wedding with my ex wife. I still rue that decision.