When a unit with 'When I conquer, draw 1' conquers a battlefield with 'When you conquer here, discard 1 then draw 1', who decides the order of the simultaneous effects?

Ruling: The controller of the effects decides the order. When you conquer a battlefield, you control both the battlefield's effect and your unit's effect, so you choose the order.

Nuances:

• Gaining control of the battlefield (conquering it) is what triggers the effects, so you control the battlefield's effect even though you don't own the physical card
• The owner of a card is the person who owns the physical card, which is different from the controller