1×9 and 1×10 on my bikes here, 32t up front but 29ers, so feels more like a 34.
Gets me up damn near anything, natural or otherwise – but then I’m fortunate to be a (relatively) young, strong, rider with the legs and lungs to attack the climbs. Sitting and spinning up something is rarely an option (though I can sit and spin up remarkably steep stuff – I’m tall with long levers).
I miss the top end more than the low end. I ride SS on the XC bike over winter, and to commute, so I’m pretty used to hauling up hills and I can spin fairly fast too.
I prefer 1x as on the AM/enduro bike the security of the chainguide is very welcome, and on the XC bike it’s also the security, less chain flapping about, less to get clogged up, a little less weight, less clutter on the bars and simpler riding – just one gear shifter to think about! I’d propose the counter argument – why have twice the complexity and those extra rings, when they bring me little benefit?
However I will say that if I wasn’t able to ride regularly enough to keep my fitness up I’d probably drop back to a triple/double. If I’ve been off the bike ill or injured the lack of low spinny gears can kick my ass a bit!