I guess I can start at the beginning... obviously some of these are from many years ago and my taste in music has since changed, but I never regret any concert I have attended!
1. Aly & AJ
2. Jonas Brothers (x2)
3. The Veronicas
4. Demi Lovato
5. Fall Out Boy (x2)
6. All time low
7. Cobra Starship
8. Metro Station
9. Hey Monday
10. 3OH!3
11. Hellogoodbye
12. Down With Webster
13. Neon Hitch
14. Dashboard Confessional
15. Nevershoutnever
16. The Cab
17. A Rocket to the Moon
18. Lady Gaga
19. O.A.R
20. Bring Me the Horizon
21. Lynard Skynard
22. A Day to Remember
23. Mayday Parade (x2)
24. A Skylit Drive
25. MGMT
26. Boys Like Girls
27. The Maine
28. Seether
29. Attack Attack
30. Foo Fighters
31. Coldplay
32. Deadmau5
33. Young the Giant
34. Foster the People
35. We the Kings
36. Mac Miller
37. My Chemical Romance
38. The Dirty Heads
39. The Lumineers
40. Of Monsters and Men
41. Edward Sharpe and the Magnetic Zeroes (x3)
42. Macklemore & Ryan Lewis
43. Four Year Strong
44. Old Crow Medicine Show
45. Twenty One Pilots (x4)
46. Blink 182
47. New Found Glory
48. Paul Mccartney
49. Eminem
50. Tom Petty & the Heartbreakers
51. Mumford & Sons (quite possibly my favorite live act) (x2)
I think that is sufficient for now. As for Festivals, I've been to Warped (2010, 2011, 2012), Rock on the Range (20??), Lollapalooza (2011), Bonnaroo (2013), Gentlemen of the Road (2013) So I included the major ones that I saw, but I definitely heard some great sets from other bands!
Currently the one band I'm a huge fan of and haven't been able to see yet is The Story So Far, so hopefully that happens in the future!