I have several favorites, so here they are:
Billy Joel - Last Play at Shea (200: I was there for the final night. Billy is probably my overall favorite artist of all-time (I'm from Long Island, so I'm a bit biased). He brought out Roger Daltrey (The Who), Tony Bennett, Garth Brooks, Steven Tyler, John Mayer, John Mellancamp, and of course, the legendary Paul McCartney. Talk about an emotional night; I will be forever grateful to my father for managing to get tickets and taking me
Adele - House of Blues Boston (2011): I have to preface this by saying I have been an Adele fan since 19 came out. I will be honest and admit that I did not listen to the album until after she won the Grammy for Chasing Pavements, but nonetheless, I have been a fan ever since. I was dating a girl from Boston at the time, and we both tried to get tickets (myself for NYC and her for Boston). She was lucky enough to get tickets (which we were offered over $1K while in line that night). The Civil Wars were the opening act; I had never heard of them, but was very impressed. I loved their cover of Billie Jean. Adele rattled off all her songs from 19 and 21 (which had just released). Hearing Hometown Glory live is something I'll never forget. I'm glad she's received the recognition she deserves since then.
JAM'N 94.5 Monster Jam - Boston(200: I honestly don't remember the opening acts (I just Googled and it was Brandy, Yung Berg, and Ne-Yo...no wonder I forgot). This concert was memorable because Jay-Z and Lil' Wayne were the headliners. Jay was on first, and then Wayne was supposed to close out the night. It turned out that Wayne refused to go through a metal detector and wasn't able to enter the arena. All the tweens in the crowd wanted to hear Lollipop and started booing. Jay came back out and said "Hey, I was gonna play some more, but if you don't want me to, I got the PJ ready on the runway." He wound up performing an additional half hour or so, rattling through hits. Amazing!
A State of Trance 600 - MSG (2013): I'm a huge house music fan. Being on the floor to see one of the biggest DJs of all-time was truly special. The opening acts were incredible (Alex M.O.R.P.H., W&W, New World Punx). Armin put on quite the show and it's a great memory
Glow in the Dark Tour - MSG (200: I've seen Kanye 7 times, but this may have been the most impressive. The opening acts were incredible. The stage production and lighting were incredible. Yeezus is god.
Musiq Soulchild,the X-Ecutioners, Common, and Kanye West - New Life Project NYC (2003): This is a show I will never forget. It was some charity event and tickets were super cheap. I was a junior in HS at the time and the show was on a Friday night. I was (still am) a Kanye fanatic and made my friends arrive to the venue 3 hours before doors. As a result, we were front row, right up against the barricades. Kanye came out into the crowd and gave us all daps at one point. Highlight of the night was Get Em' High (my favorite Ye' song still to this day).
Honorable Mentions:
Watch the Throne Tour
Usher Confessions Tour (with Kanye)
Clipse (Live at Middle East - Boston)
New Found Glory & Blink 182 (Jones Beach)
Billboard Festival 2015 (Jones Beach)
Tiesto - NYE 2013 (Ovation Hall - Revel AC)
Above & Beyond (Echostage 2013)