Fine as is, lifetime appointments
Limited terms, one term only
Limited terms, but allow multiple terms if re-confirmed
As much as you might want justices that judge things based solely on their interpretation of the constitution, it's completely unrealistic. People are biased about things, and none of us are very good at preventing our bias from influencing our thinking.
I do agree that justices should be appointed for life though. I think it limits somewhat the degree to which politics affects their opinions.
If you build a man a fire, he'll be warm for a day.
If you set a man on fire, he'll be warm for the rest of his life.