Best Online Strategy Game? Depends on Your Taste—Tell Me Your Preferences

No single "best"—it depends on what you want. Tell me:

• Genre: RTS, TBS, Grand Strategy, 4X?
• Setting: Fantasy, Sci-Fi, Historical, Modern?
• Complexity: Easy to learn vs. deep/complex?
• Multiplayer: Competitive, co-op, or single-player?
• Cost: Free-to-play or premium?

Answer these for personalized recommendations!