Along with most of the ones already mentioned, going really old school for these:
Masters of Orion 2
Heroes of Might and Magic 3 (With both expansions)
Jagged Alliance 2
Warlords 3: Darklords Rising
Age of Wonders: Shadow Magic. Though the original Age of Wonders probably has a better campaign storyline though since it has multiple branches. Had a bit more charm somehow as well. Some armies weren’t as balanced in the original and with the right equipment, it is completely possible to send a high level hero to wipe out an entire city garrison all by himself. Always liked the little lore bits that accompanied each unit.