Gravel bike used on pavement occasionally and rolling or even longish hills that VT is famous for, I prefer 2x as the cassette often has closer gears that are useful to maintain a decent cadence. While I like my 1X system for mt. biking where I do a lot of quick up and downs, I prefer 2X on my gravel bike. My Topstone with a 30/46 crank and 11-34 11 spd. Cassette gives me 19 different gears. A 1x is only the number of gears on the cassette, 11 or 12. Why give up gears. Note though that depending on the 1X system, you might get a cassette with lower gears than on a 2X, my 1x 12 spd. Cassette has a 50 tooth, which is significantly lower than the 34 on my gravel bike, so if you know the hills are super steep, sometimes a 1x gets you the gearing to be able to climb. YMMV