My favourite concert ever was a Maiden outdoor performance in Montreal in 08. Will never forget Ryme of the Ancient Mariner.
BUT, having said that, in 1984, I went to see Miller Music Fest at Jarry Park, and the Eurythmics blew everyone away. It was proportionally the heaviest concert I have ever seen.
I had a completely different understanding of Dave Stewart after that concert, and I just hear their music differently since then.