To live on Mars, we'd have to genetically modify people to live in the low-Gee, lower air-pressure.
All things considered, a fully terraformed Venus would be a lot more desirable for humans, than a fully terraformed Mars.
But, if humans live in space, (they're the ones that most likely will terraform them), they may not desire living in such high-gravity worlds. (Think the Expanse, so to speak (I hate referencing sci-fi)).
Trying to learn a little more science here; What is the benefit of changing Venus' spin?
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There's no problem with it rotating, retrograde, for humans. However, it's slow rotation means that with the greenhouse-atmosphere gone and an Earth-like one in its place, temperature-maps put the equator-continent as having a daytime temperature of over 100°C.