US festival for sure, and likely the 1967 Monterey Pop Festival. I might want to see a few acts (Santana) at Woodstock, but so many other festivals were better organized and had great line ups.

I would not call it a festival as it was one of Richard Blade's one night compilation concerts at the MicroSoft in DTLA, but among the bands playing were Wang Chung, Flock of Seagulls, MC Hammer, Josie Cotton, Violent Femmes, Dramarama, Big Country (obviously without the lead singer who has passed, and China Crisis. Heaven 17 was supposed to play as well (a personal favorite of mine), but something happened and they had to cancel.