I have a lot of favorites, but my absolute favorite is "Under the Bridge" by Red Hot Chili Peppers. It really cheered me up when I was having a bad day.
Some of my favorite songs are Karusell by Leroy Styles vs. Sunnery James & Ryan Marciano, Lunatic by Dj Snake & Mercer, Ritmo by Noizekid, almost every Wiwek song (especially Trouble [w/ Gregor Salto]), Hollywood by Afrojack & Hardwell, just any Martin Garrix song (except the original version of Animals)