I already gave you the answer why Mars is a better colonization target. It's resources. This effects both setup and sustanance costs as well as just plain survivability.

The idea that an NEO compares to a planet sized world is laughable. They are resources of pitiful extent compared to planet sized worlds like the Moon and Mars and require basically the same or more energy to reach and exploit. They would make great resources for space based industry if we had it, but we don't. Starting there other than by dovetailing with diversion studies would be putting the cart before the horse.

O'neill colonies are far more technically challenging than any other option and are also the most resource challenged. That's the reason they aren't discussed much anymore now days even by the descendent organization of the one that once sponsored them (NSS from L-5).

The Moon and Mars are far better colony choices and Mars is far better than the Moon. The Moon is extremely poor in two fundamental requirements for life - water and carbon. Mars is also far richer in nitrogen. All of these resources are readily available on Mars but require shipment from Earth or a huge input of energy per pound produced to recover from the scant sources on the Moon. Water is at best a trace component in a few lunar polar craters while it makes up nearly 50% by volume at the surface over a wide portion of Mars. Mars has C,O, and N all easily captured from its atmosphere while they have to be mined from lunar soil or shipped to the Moon. It costs thousands of dollars per pound to ship anything to Mars or the Moon. It should be obvious to anyone with brains that readily available resources are key to making any long term habitation in space relatively inexpensive and practical to maintain.

If you want to pick a place where we can go and stay permanently for the least cost the obvious answer is Mars. So if you place any value on the second home for humanity issue you shouldn't be handwaiving away Mars. The die hard stubborn support for Mars comes not from Mars Face type nuts, but practical engineers and those that can understand their reasoning. There are other prisms through which to view the where next issue, but frankly the leading alternative space business model has been looking pretty silly up until Rutan's recent triumph and he's a very long way even from getting to LEO. Pick whichever you want, I can usually make a case that Mars is at least comparable to another destination through another goal or that the goal itself is far less worthy than those that favor Mars.

Regards,
Mark