>>1947737The frame shell width and spindle length are two independent numbers. You'll need to stick to a 68mm wide BB for this frame regardless of anything else, but the spindle length depends on the crankset you're going to install. If you're not changing cranksets then you do need to stick to 127mm, otherwise the crankset will bottom out against the frame/chainstays if you try to install on it on a too-short spindle.
>>1947282It really depends on the kind of riding you're doing and also personal preference. I own bikes with all those drivetrains and have ridden older bikes extensively and I have strong preference for closely spaced cassettes for anything that isn't technical trail riding. I don't mind a wide 1x12 for mountain biking because being able to keep your gear ratio/cadence dialed just isn't very important when you're on a trail and shifting your body weight around the bike a lot. But on pavement it does make a big difference for efficiency to be able to get into the exact ratio you want, and I find that same 1x12 is a little frustrating to use when I have to ride on the road to get between trail segments since I'm so accustomed to having that with road and gravel bikes. I would actually prefer to have a 3x8 drivetrain with a tight cassette over a 1x12 for road use, I had that on my do-everything bike for years and years and its was both pleasant to ride and had great range.
