Open vs Closed-System Vape Devices cost

Which is cheaper in the long run: open vs closed-system vapes. Open-system vapes let you refill your own e-liquid, which seems like it could save money over time since you’re only swapping out coils. But the upfront cost can be a bit higher, especially if you go for a more advanced model.

Closed-system vapes are more convenient with pre-filled pods, but those pods can get expensive fast since you have to replace them regularly.

Which do you guys think is more cost-effective?