Here are my basic "go to" gear.
As you can tell, I have joined the Canon side.
My go to when shooting a concert are the three different lens in this image: 50mm, 27-70mm, and 70-200mm.
As for the Camera I use a 5D Mark III, and a 5D Mark II as back up.
Also shown is a Colour Checker that I mainly use when doing portraits and outdoor images. I don't use it when at an event.
As well, I have many memory cards, as I like to switch while shooting, just incase one is to get corrupted.
For my flash, it is an 430EX II and a Manfrotto Tripod for when I am doing long exposure images.