Like many people I like things that stand out, unusual things.
That's why I like the Kirov-class battlecruiser.
It's the largest non-carrier warship in the world, the last battlecruiser, it's size about the same as the lower-end gun-armed battlecruisers of wwI-wwII.
The other interesting one is the military underwater resue ship Kommuna. Comissioned in 1915 as a submarine tender and it has been in continues service since then, being continuously updated and refitted, turning from submarine tender to basically rescue divers carrier. If they don't make a museum ship out of it at the end of it's service- they are all faggots of the highest order.