For me, AoE original for playing AoE civs, RoR for playing RoR civs. I like them both, have warm feelings for them both, but strongly agree that the overall vibe of each one is very different. AoE fits the nascent world setting, RoR is much more like “angry armies subjugating the unruly tribes” to me.
And something mildly related: AoK came out in my country WITHOUT background music, only the main menu theme. Imagine my surprise when all these years later I first ran AoK HD on Steam that obviously plays music. “Wow this thing has a soundtrack.”