Doug: For this guy, my entry to the Avengers on an ongoing basis was around #119-120: the adventure against the Collector in Rutland, Vermont and then on into the Zodiac arc. You can see from the cover below (Jazzy Johnny Romita had a hand in that one, ya think?) that our Avengers at the time were Thor, Iron Man, Captain America, the Black Panther, the Vision, the Scarlet Witch, and Mantis and the Swordsman. That's a great line-up, certainly one of the best in the history of the team.
Karen: That's a powerhouse line-up, and very similar to my first team of Assemblers, from way back in issue #92. Anyone who's been around here for more than a few months knows that I came aboard the Marvel train with the Kree-Skrull War and never shut up about how great it is. But my first exposure to the Avengers had a team divided: there was the active team composed of the later generations of Avengers, namely the Scarlet Witch, her brother Quicksilver, their comrade Clint Barton, once Hawkeye, now playing the role of Goliath, and the Vision. The Big Three -Captain America, Iron Man, and Thor -show up at the end of the issue to disband the team -although they were really Skrulls posing as those heroes. But by the next issue the real McCoys would be back, along with a brief visit from Ant-Man. So I always think of the Big Three, plus the Vision, and Wanda, as mainstays.
Martinex1: As I've mentioned before, at a young age my cousin gave me a box of various comics and my favorites amongst those were a smattering of Avengers books ranging intermittently from Avengers #45 to Avengers #91. So I received in that gift a pretty broad view of the team's assembled heroes. My favorite though was the team gathered in the battle with Grandmaster and Kang in issues #69 to #71. The final page of that arc had a marvelous Sal Buscema pin-up that defined the team for me; it included the big three plus Vision, Clint-Goliath, Yellowjacket, Wasp, Black Knight, and the Black Panther. When I purchased my first Avengers comic with my own money, it was at the start of the Nefaria Saga at issue #164. Amazingly the team had not changed much despite the big gap in issues. The main difference was that the Scarlet Witch and the Beast were in, but Clint and the Black Knight were absent. So those were essentially my Avengers! I do have to say though that I thoroughly enjoyed the second kooky quartet that Karen mentioned of Goliath, Vision, Scarlet Witch and Quicksilver; their battle with Brainchild in issue #86 remains one of my guilty pleasures in following the team.
Redartz: My introductory Avengers lineup is quite similar to Doug's, as we joined the Assemblers during the same era. Specifically, I began with issue # 127, the crossover with the Inhumans and the Fantastic Four. Actually, I bought the issue because of the Fantastic Four appearance, and was immediately hooked (and why not -- what a cast of characters, and Ultron to boot!). So that would be Thor, Iron Man, Wanda and the Vision, Mantis and the Swordsman. Honorable mention goes to the Beast, who joined shortly thereafter, and became my favorite Avenger.