I'd suggest these three:

1/    Myrdal to Flam (Norway). No cogs, no cables, just 5 sets of brakes as it descends 900 metres in 20 kilometres to the south arm of the Sognefiord with views that are out of this world

2/    Centovalli Railway from Locarno to Domodossola. Only the Swiss could see nothing comical in putting the company's initials on the side of the train - even if the result is F.A.R.T. Must be one of the most photographed trains in Europe.

3/   And Victoria, Australia's much loved Puffing Billy. An old logging narrow gauge line that the authorities have tried to kill off for more than 50 years. Exclusively steam powered & run by a local Preservation Society, it chugs through the hills every weekend & sometimes (holidays) during the week for 20 odd miles & even races runners over 6 miles in an annual race (for the record, it usually beats about half the field home). Along with the Healesville Sanctuary (see every Australian native animal at very close range) & the Yarra (the only river known to man where the mud flows on top of the water), Puffing Billy completes the list of genuine tourist attractions in Melbourne.

Cheers

Dave