I think it is 35mm.
I used to carry 15-30mm, 24mm, 35mm, 70-200mm for the longest amount of time for all my trips. This time round I bought a sony a7riii just before the holidays. Sold my nikon D800, 70-200mm.
Now my gear is
D750 with 15-30mm or 24mm f1.4
sony a7riii with sony 35mm f1.4 or 85mm f1.8.
The sony has an APSC mode that will magnify your viewfinder to APSC crop making your 85mm to around 130mm. Previously, I did not switch to mirrorless because of the AFC performance. I think a7riii is the first mirrorless that is as good as my nikon in AFC and within my budget.
After this trip, I am probably convinced sony mirror less is the way to go. The AFC, viewfinder, weight all beats my D750....
I came from a humble Canon 1000D.
Very basic but Canon has great skin tones reproduction.
Sold it and got myself a Bridge Panasonic Lumix FZ1000.
Panasonic FZ1000 has a very overly sharpened photo. Worst than Canon albeit costlier than my Canon 1000D.
But it has 4K recording, which was what pushes me to start doing videography more than photography.
Done my 2016 and 2017 Girls of the Singapore Motor Show and then very recently my Hong Kong trip with gimbal and really loses my arm carrying the 1.5 kg payload daily for 5 days , morning to night.
Hence decided to sell it for a brand new Olympus E-M10 mark III.
The Mark III is the lightest MFT camera I've ever own for a camera.
Fantastic small compact and retro looking camera.
Weak resolution at 14M pixel for today's standard.
Compared to your a7R-III , its 1/3 your sensor.
My point here is, there is no best camera out here for your usage pattern.
Over the years, as your habits change, utilization shifts, it became nature for one to change camera gear to adapt to the best of one's shooting characteristic.
And you notice my gear didn't really leaped in specfication, only features.
It was a from still photography camera, to a DSLR sized bridged camera to a pocket sized micro four-thirds. Odd progress for me,.. oddly I liked the Olympus today than my previous cameras.
It's PNE ! PLay Not Enough lah...