Cactus Preserve

It doesn’t matter where your commander is (or commanders are, if you have more than one because of the partner ability or similar). The value of X will be calculated using your commander’s current characteristics. (Mana value typically doesn’t change, but your commander may become a copy of something else.)

Cactus Preserve’s second ability checks the effects of all mana-producing abilities of lands you control, but it doesn’t check their costs or legality. For example, Spire of Industry says “{T}, Pay 1 life: Add one mana of any color. Activate only if you control an artifact.” If you control Spire of Industry and Cactus Preserve, you can tap Cactus Preserve for any color of mana. It doesn’t matter whether you control an artifact, whether you can pay 1 life, or whether Spire of Industry is untapped.

Cactus Preserve doesn’t care about any restrictions or riders your lands put on the mana they produce, such as that of Bucolic Ranch or the ability granted by Discreet Retreat. It just produces one mana of the appropriate type, with no restrictions or riders.