Hi. Everyone is going to have to make their own decisions here on these two. As another poster has said, the Trumpeter has a lot more seperate parts to it to build, with over 1100 pieces overall, compared to around 700 for the Dragon kit. One of the main differences here is in the amount of seperate parts there are that go on the two trucks.
Also the Trumpter kit has the L- or T-track to it as well, depending on how you want to display it. Both have PE, hoses, wire and such to them.
But you are going to pay around $30 more for the Trumpeter kit Don't think you can go wrong with either of them, from what I've seen of them both in the box. I opted for the Trumpeter model due to the different track layout that is a option. Although I plan, if all goes well and it can be done, to build the in-line version of it with the model RR accessories for the track, rails, ballast and bed.
If you're concerned about the price of the Trumpeter kit just look at it, what with all the detail involved in building the two trucks, cradle, gun and track bed, as like getting 5 seperate kits all in one box.
And just because it comes in a big box don't thing for a second that there's lots of empty space in there. This carboard container is chock full to the gills with parts, top to bottom. So you are going to get your money's worth. And it it also packages very nicely with some extra packing around those easily breakable parts.
Good luck and take care, sgirty