This will always be a double-edged sword as the tires featuring the bigger, gripper knobs are always going to grip better in the dirt at the expense of tarmac efficiency, and vice versa.
In our opinion, it’s about choosing what’s best for you and your riding – if you’re riding predominantly on road, then choose a slimline tire that’s going to save you watts on the tarmac. But if your riding is mostly in the wilderness, something with a reliable bite and sidewall support is going to be much more rewarding when things get spicy.