Many years ago I came across a leather bag in a little boutique in Whistler, BC that was my 'dream' satchel. It was natural leather, unisex, simple, classic and beyond my price range. I had forgotten the name of it until now. The brand is BREE and they're German. Check out their website (not an affiliate).
Filson Leather Field Satchel - Valextra
Mulberry - BREE Elch nature
etsy seller gdirrt - BREE Homme 3