We should do it all
We will be sending lots of robots in the next couple of decades and that is good. I am sure we will gain lots of knowlege and maybe even find/prove some sort of life.
I hope when humans go it will be part of a long range plan to set up a permanent presence there. I would not really favor a one-shot flag and footprint mission. It will always be shrouded in mystery. When the population of Mars is over a million the Martian tabloids will be reporting bigfoot sightings.