This is home owner preference, I install mostly steel, tar covered tanks. The draw back of steel is rust. Life expectancy has a lot of variables, but typically around 15-25 years. Some people swear by plastic or fiberglass tanks, but with our extreme freeze thaw cycles and bury depth I believe they are more susceptible to fracture and collapse. Concrete tanks are great, the only draw back is their excessive weight (10,000lbs+) so a crane is needed to set them, which also means you need a lot more area for a crane to set up.