The best train line in Queensland has got to be the Kuranda Scenic Railway, mainly because it combines so many memorable aspects about a train trip. However, there are still several others worth discussing. Around Toowoomba, the train line is very winding and slow, so it's quite a remarkable experience. The Spirit of the Outback has winding mountainous moments when up on those Central Highlands, yet the desolate fields, semi-desert and anthills are such a fascinating combination as far as long-distance train trips go. Keep in mind each line has a name but the service that travels that line is also a fine answer. Sometimes the line is very long when travelling far into the state, hence naming the service sort of is like naming the line - e.g. the Spirit of the Outback is a much more recognisable answer than the Central Western Line. Some history of Queensland and Brisbane's railways can be found at the State Library of Queensland blog.
I'm yet to try the Inlander from Townsville to Mount Isa, while it's mainly travelled by night, and although Mount Isa is known for mainly mining, the entire experience is well respected amongst train tripping enthusiasts. As featured on wexas.com and in their top ten Australian train journeys, Queensland occupies five places in an overseas travel agency list that includes the big Australian journeys such as The Ghan and Indian Pacific. This list also includes The Gulflander, which is a very interesting train trip near the Gulf of Carpentaria in the state's north.
The Sunshine Coastline is surprisingly nice - with its cane, pineapples and hinterland scenery while the Gold Coast line is very busy and hectic - especially given its connection to G-Link light rail. The Gold Coastline is connected to the Airtrain. I've never done the Airtrain proper but have seen the stations out at the airport - they are very conveniently placed and the trains themselves are quite comfortable - I know that because they are usually a continuation of the Gold Coast trains.
The Spirit of Queensland and Tilt Trains are nice, especially on those lonely plains and there are some jaw-dropping bridges and scenes. Often the trips are long and hence gruelling, and I've been too tired to fully realise how intense the scenes are, but, looking back, you realise you've seen amazing mountains, waterways and bridges. The train service that preceded the Spirit of Queensland was The Sunlander - a quirky fact and historical point of mention.
Ipswich Line has its moments in my opinion - especially all the way out to the Rosewood Railway. Cleveland, Beenleigh, Ipswich, Caboolture and Ferny Grove lines are long, commuting lines. They don't last long enough to be outright journeys but last long in the crowded commute. The busyness is the excitement of those lines - they aren't sleepy but are not all that big on scenery either. They're busy commuter lines.
Shorncliffe and Doomben are very nice inner-city lines, going to places such as Ascot Station, the Golden Circle Cannery, and the seaside. Springfield and Redcliffe are new lines and cover some old tracks before branching off into newer track. Great ideas for making those places in reach of the Brisbane CBD.
So, given how Queensland can make train travel anything but dull, what is Queensland's best passenger train line?