nobody mentioned Age of Empires II yet
I recently started playing the Definitive Edition and it's absolute peak. Especially with the new DLCs, which are all pretty cheap, there's a shitload of campaigns to play through and they're all of good quality. Multiplayer is fun too but you will lose a lot at first as a noob.
It was my favorite game as a kid, and it still holds up. If you're new to strategy games and only played Star Craft, it's a great game to get you deeper into the genre. It adds several layers of complexity and nuance compared to Star Craft, with a bigger focus on macro than micro, without being overly complex. It's easy to learn and hard to master.
You get 4 resources: wood, food, gold, stone. Wood is used for buildings, food for recruiting villagers, most military units require gold, and stone is exclusively for fortifications. The one rote task you need to learn is to constantly queue villagers in your town center, you gotta keep pumping those dudes out so they can gather resources, but what you do with them is a major strategic decision: do you prioritize wood, gold, or stone? How many farms do you build? Depending on what kind of military you want to go for, you'd want to prioritize different resources. Wood and gold for archers, food and gold for knights.
There's a big enough variety of units to make tactics interesting, and because gold and stone are important but scarce, achieving map control is important.
The campaigns offer a great variety of mission goals, and many are quite challenging (especially the new DLC campaigns).
As far as traditional RTS games go, AoE2 is the best in the genre. Its lasting popularity is testament to its excellence. A team of modders was working on a big content mod for the game, then Microsoft hired them to remaster the game, which they did. Their mod was turned into an official DLC, and then they made two more DLCs... after which the game was remastered
again, much more thoroughly this time, and Definitive Edition is the best example of how to remaster a classic. None of the gameplay was changed, but a lot of QoL features were added, and some of the weaker campaign levels were overhauled, and they added three more campaigns! And now they keep pumping out DLC for it, and the game has an incredibly active multiplayer scene, as well as mods that add new campaigns and gameplay modes.
In fact the game has a more active playerbase than the new sequel AoE4. It's an enduring classic for a reason. I've been an RTS fan since my childhood, but not a single game in this genre has managed to surpass AoE2. It's just that good.