Star Destroyers of course have been one of the most iconic parts of the franchise since the first film, and of course have gone through many changes over the years. Any particular favorites?
Acclamator-the proto-Star Destroyers seen in AOTC. Also the first Star Destroyer style ships we see able to land/operate in an atmosphere, which would pretty much become the norm later on.
Venator-The Star Destroyers seen in ROTS with dual bridges. Seen in red Republic colors but then in Imperial grey by the end of the film.
Imperial I-The original Star Destroyer design seen in ANH and revisited in Rogue One. Biggest differences are the level of detail and the bridge tower design.
Imperial II-The updated model used for the sequels with more detail and other changes.
Resurgent-The Star Destroyer class seen in the sequel trilogy, resembling the Imperial design but with the bridge closer to the rest of the hull and larger than it's predecessor.
Mega-Represented by Snoke's ship the Supremacy. Also has more of a boomerang design.
Executor-Represented by Vader's ship. AKA as Super Star Destroyer.
Others-I suppose you could put the Dreadnought in this category, as well as the various Clone Wars and Rebels variants.