First Contact just doesn't do anything for me. It feels the most like a TV episode to me, depending the most on TV elements (Borg, Zephram Cochrane, time travel) for its story.
I think most fans like First Contact because of its connections to the show. It was a loose sequel to BOBW.
It's the same reason why many fans consider TWOK to be the best TOS film since it had Khan, who had once appeared on that series. Ricardo Montalbán's brilliant performance helped too.