I use both meths and butane in my models (although not both at the same time
). Butane is clean and easy if you get the burner /jet set up correctly but meths is a lot more fun. As far as performance is concerned, there is very little difference between the two fuels in my experience ……again depending on boiler / burner setup.
Before you waste money on gas soldering irons, you can get "Ronson type" gas fillers cheaply on EBAY. You will also need a suitable tap for them though. I don't have the information immediately to hand but I seem to recall that it is M4.5.
Mick