I cannot suggest which gauge is better, but I went with O-gauge (32mm) as I have about a dozen or so 100 year old Bings, Märklin, and Carette locos, along with my Bowmans and Mamods that are all O-gauge. When I someday get an outdoor layout going I am going to use dual-gauge track from Sunset Valley Railroad so I can also run G-gauge (45mm).
Sunset Valley track comes unassembled in 6ft sections. Code 250 rail is available in brass, aluminum and stainless steel.