There are too many for me, mainly because of money, it is expensive to watch bands in Mexico when you don't live in Mexico City. Some bands I missed that I regret:
Transatlantic, VUUR, Alestorm, The Aristocrats, Babymetal, Dream Theater in the BC&SL tour (the only DT show I've missed since I became a fan in 2007), Mayan, Ghost, Mastodon and many others.