Would you get a spring air gun or a co2?

Here's the advantage and disadvantage.

Spring airguns (Not airsoft) usually have more power than C02. Spring airguns and rifles can reach speeds up to 1650 FPS (Feet per second0 but they are single shot guns and rifles so you have to reload between shots.

C02 guns and rifles attain a speed up to 650 FPS but will give you multiple shots between loads. You can usually get about 60 to 80 shots from a 12 gram C02 cylinder. However you should never leave a C02 charged cylinder in an air gun because the constant pressure may eventually damage the seal. Or someone else may puck up the gun later and fire it not knowing it's charged and possibly loaded.

Never leave a spring air gun cocked it's will eventually damage the spring.