I like the Ice Path/Cave in Johto but absolutely despise the Rock Tunnel in Kanto(Gen.1). I like the Ice Path simply because it was the first cave to feature a completely icy layout. The reason I hate the Rock Tunnel so much is because when I was first playing Red all those years ago I would always get stuck in there for hours and my Pokemon would get owned by all the Hikers and their self-destructing Gravelers.