The next best terraforming candidate, Venus could provide to be more attractive than Mars. We do have the technology to cause massive precipitations in the extensive clouds by exloding huge tanks of liquid nitrogen in the upper atmosphere and cause the temperature to drom, causing condensation, precipitation and eventually, some major openings in the cloud cover that would allow the planet to expel heat radiation into space. There is oxygen and water on Venus, in small concentrations but with a little help, they could initiate a chain reaction that would alter the planet's "ecology".
