It is said Mars moons are easier to reach than iur Moon because of a lower Delta V to get there.
And therefore, Mars is also more accessible.

I'm not convinced because Mars problem is the distance or the time to get to it (If the argument is "we'll reach Mars with better propulsion methods", then the Delta V argument falls flat) much more than the energy to get there.

Time has many aspects to it:

What happens to the organism after 3 years in weightlessness?
What happens to our well being and efficiency and psychology after years in space and on another world?
Can we practice 2 hours of gym every day for 3 years, without interruption?
What happens when a solar flare hits the spacecraft, or gamma-rays reaching it from 2 neutron stars colliding in the other side of the galaxy?
What happens to the fuel carried by the spacecraft after so many months? The russians won't let their Soyuz more than 200 days in space (because the H2O2 becomes H2-O2 and looses its properties); I read about issues from hydrazine in their tanks after a month in space. There is the risk of evaporation, or corrosion, metal being attacked by the fuel.

The problem is: all those issues need to be tested and testing means many many months (or rather years) before the tests are satisfactory (if they are), precisely because it's the test of time.
And time means patience, not only for the astronauts, not only for the scientists, technicians, but also (and more importantly) for the public, the media and the congressmen.

For the Moon, it's very different! It takes 3 days to get there and 3 days to get back; the Sun energy is at the same level as in Earth orbit. The Moon can become a shelter.
The media are much more intersted in an event lasting one week or two, but a much longer time cannot attract their attention (and the public's) the same way.

Raoul