We have lots of brains in this planet. We can work in both efforts or even more than these two.

There is no point in arguing which one is easier. Feasibility and difficulty shouldn't be reasons for discarding long term efforts. Many current ideas were seen as impossible or extremely difficult.

I agree. I also noted in another comment that these things aren't mutually exclusive. Rather than "why try any of these things?", we should ask "why not try all?"

Getting people to Mars is the easy part. Making Mars sustainable is a lot more difficult.

AGI solves the existential problem better than just moving people. If you can bundle intelligence on an SSD (metaphorically) you can send that outside of the solar system.

We have, to a good approximation, no clue how human biology achieves intelligence. I'd say it is far more realizable to go to Mars than to put a brain in a flash drive. Even if we achieve AGI, that isn't (necessarily) a human intelligence.