Standard will finally rotate next week, for the first time in two years. Some of my decks with survive, with a few changes, and some won't. But when I think about it, I don't think there are any cards in the whole year's worth of disappearing sets that I'm really sad to see go, except for the five channel lands from Neon Kamigawa.
They're basically perfectly designed: useful without being overpowered. Very few decks want four copies of them, but most decks benefit from having one or two in the appropriate colors. With the possible exception of Slogurk legends, decks aren't built around them, and games don't hinge on whether you draw one or not. Their abilities are moderately powerful and fairly costed. They help mitigate mana flood. Their legendary status makes them self-regulating.
I do my share of complaining when I think Wizards gets something wrong, so I don't want to neglect to mention what they get right. The channel lands were a great design and I'll miss not being able to put them in my Standard decks.