Great idea for a thread! I love discovering new stuff at festivals. Next month I am travelling to Bristol to see a band I first saw in the Bimble Inn at my first Glasto in 2014 and they blew me away (Will and the People if anyone is interested) and also Smoove and Turell who I've seen a couple of times at Glasto too.
One of my favourite bands is Man and the Echo who I discovered in the Left Field in 2016 - brilliant act who I've probably seen getting on for 10 times since.
I agree with the idea expressed on here before that smaller acts should be announced earlier than the well-known acts so that punters have time to listen to them in advance.