Trypticon, the Decepticon city/battle platform/huge as T-Rex, was an awesome Transformers toy back in 1986. In "city mode," you could connect the Stunticon and Combaticon teams to Tryps somehow, making it look more like an actual little city.
Some of the Masterpiece Transformers are pretty impressive, too, though I tend to regard those more as display pieces than actual toys.
The G.I. Joe: A Real American Hero line of the 80s and 90s had some kick-ass stuff, too. The Terror Drome, the USS Defiant and its launch complex ... lots of the vehicles were really cool, too. I always liked the COBRA stuff but the Joe team often had bigger shit to mess with, like that one mobile battle fortress. Can't remember its name. (Ah: the "Mobile Command Center." Creative

.)