This is not an entirely uninformed judgement call. I had seen 19 sets in 2012 and Glen Campbell at Town Hall was easily the best. The man is ill but the music gave hi a second life, and surrounded by his two sons and daughter, and with a very good album to promote, he performed an act of pure shamanism.
How Campbell managed to maintain his cheer, his demeanor, his happiness, in a situation that, simple age not being the only problem, but with his life drawing to a close, is a testament to music and to a certain power of faith and good will.
The second best was Volbeat,. Third in the line-up for Gigantour. I had heard exactly one Volbeat album at the time and it hadn't particularly impressed me, but with Motorhead and Megadeth, both playing great sets, Volbeat were the Giants to beat.