Who is YOUR favorite band?
Take your time. This is a tough one. Personally, I don't think I can pick one favorite. I can just name a few I like a lot. I like to listen to a variety of music ranging from Rock, Alternative, Metal, Country, Oldies, Pop, and Contemporary. (pretty screwed up list, huh?) I have been to dozens of concerts, ranging from outdoor Warped Tour to smaller venues with local bands. One of my favorites was an A Day to Remember concert, they came out with toilet paper guns and shot them into the crowd while exploding confetti everywhere. It was so fun!
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With songs like Feeling This, I Miss You, Another Girl Another Planet, Dammit, M+M, What's My Age Again, and The Rock Show, how could you not like them?!
I have not seen them live...yet.
21 Pilots
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Disclaimer: I fully expect my brother to comment on this.
You see, he showed me this band earlier on and I wasn't too impressed. However, when I met 
Bowling For Soup
I recently started listening to them even though they've been around for awhile, and they are one of my favorites. Some of the best songs being 1985, Ohio (Come Back to Texas), Almost, Everything to Me, Punk Rock 101, No Hablo Ingles, and High School Never Ends.
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Of course they made it to the list! If you have a pulse, you've heard of The Beatles! I grew up with my Dad listening to them and continue to listen to them today. It's one of the bands that never goes out of style. Some of my favorites (along with everyone else's) include A Hard Day's Night, Hey Jude, Let It be, Come Together, We Can Work It Out, I Want To Hold Your Hand, and All You Need Is Love.
More mentions I would include is Boston, Linkin Park, Zac Brown Band, Home Free, ZZ Top, Close Your Eyes, 3 Doors Down, Green Day, and more I will think of after I hit post.