If either range works for your riding, use whatever is cheaper. Drivetrain is wear, and RD get damaged on MTB. Sooner or later you replace them anyway.
Much more important to get better geometry, suspension etc.
As for outdated: if you are OK with the range of 10 speed, you are only missing the better shifter, like XT with double-up shift etc.
1 issue with wide range 10 speed is you get large steps between each gear. Doesn't mean it is outdated, just something to consider.