The fourth season premiere of Voyager was a game-changer for the series, carrying a number of responsibilities: opening the season, concluding the "Scorpion" story, introducing Jeri Ryan as Seven of Nine, and boosting ratings.
The success rate of these ambitions was certainly high, considering Seven was an immediate breakout favorite among fans, and Jeri Ryan herself became a mainstream star, whose career is one of the few to survive into regular work outside of her Star Trek experiences.
This is an episode any franchise fan can enjoy even if they're not particularly a fan of the series, though series fans will certainly enjoy it as well, without question. The inclusion and effective use of the Borg is a rare moment where the Next Generation made a notable impact outside of "Best of Both Worlds" and First Contact, something that was surprisingly rare for the fan favorite villains. It is an essential episode for the series, and can be viewed as a spotlight for several characters, including Seven, Janeway, and Chakotay.
Having all four distinguishing features of a Star Trek episode, this one is a franchise standout.
Franchise * Series * Character * Essential
Memory Alpha summary.