From an energy-efficiency perspective, the difference is negligible. Getting out of the gravity well is by far the biggest hurdle. From there you might as well just give it a gentle push over to mars.

I see that you have not reckoned with how deep in the sun's gravity well Venus is.

Why waste precious carbon that could be turned into life, industrial equipment, and fuel when energy from the sun is plentiful and otherwise wasted as it radiates into space?

Probably carbon extracted from Vesusian CO2 should be made into diamonds, to resist combustion, and dropped to the surface.

Importing enough hydrogen to take up excess released oxygen will be difficult.