My current project is a top-down space shooter where the player commands a capital ship with increasingly powerful armaments and alien artifacts. Primary ship components would include: main turret, missiles, armor (health), shields, flak (auto-defense weapons) and possibly engines.

I'm considering two different models for purchased upgrades:

1. The player spends money upgrading items along a single path. Turret I, Turret II, Armor V, etc. The player could choose to upgrade from Turret I to Turret II for $5000 and get a faster, more powerful weapon, or the player could choose to upgrade from Armor II to Armor III for $6500 and have better protection.

2. The player spends money purchasing upgrades that enhance one property of a component. For example, the player could spend $2000 increasing turret speed, or $1500 increasing turret damage, or $1000 increasing his shield's recharge rate.

The second model gives more choices, the first is less confusing.

Which would you go with?