Oh boy, classic roller coasters, I'm a sucker for all of them. Because it is top of mind with the removal of the Wildwater Kingdom slides recently, the Big Dipper at Geauga Lake was a top sentiment - it was the roller coaster growing up in Northeast Ohio (The Double Loop too for those willing to go upside down). Once Geauga Lake closed, Big Dipper turned into a bastion of last hope for the property and it's deep history dating back to 1887 - still standing for years as Cedar Fair sought to sell off the property. So, it's removal last year was not just a loss to roller coaster history, but an entire region's past tourist history.
I had Ravine Flyer II ranked as my #1 woodie for years too out of sentiment (and it's still a damn good ride too) - the notion of resurrecting the original Ravine Flyer concept was so romantic, and gave a cool modern view on thrill rides of the early 20th century.
Finally, my current avatar set is of the Wildcat at Idora Park, a former amusement park in Youngstown, Ohio. While I never had the chance to visit the park (it suffered a business ending fire in the mid-80s), it was a derelict structure I remember seeing for years growing up (the park property is located next to a state park). I also enjoyed seeing nature reclaim the old wooden structure, and imagining what it would have looked like in it's heyday.