I have both a new gravel bike and an older XC hardtail turned monster gravel bike. For smooth gravel, it is hard to beat the gravel bike. It is much more efficient. For chunky gravel, I much prefer my XC hardtail. I love being able to rip the descents while those on their gravel bikes are struggling to make it down.
It helps that my XC hardtail basically weighs the same as my gravel bike.
