Digital, because I wanted to try it out, and because I liked the idea of incorporating some degree of computer control.
With hindsight, the combination of N-gauge with digital does impose some limitations I wasn’t anticipating: reduced choice of decoders; limitations on extra functions; fiddliness of installing decoders yourself if the loco doesn’t have a built-in interface. But on balance I think it’s worth it.
After a small-scale test with a loop of track and one loco, I decided that I was going to stick with digital.
At the moment, I’m using an Intellibox, loco decoders mostly also from Uhlenbrock, and a mixture of Tams and Littfinski decoders for points and signals. For the point decoders, I soon found that you do have to follow the manufacturer’s advice and connect the power supply direct to the transformer, rather than using the digital signal, otherwise there isn’t enough oomph to keep the fleischmann point motors working when they get a little stiff.
Feedback is by current detection, using Uhlenbrock Loconet modules (63340). I chose this approach as more elegant than reed switches and magnets, and it seems to work well, but it does work out fairly expensive. A minor drawback is that you have to make carriages and wagons draw some current so that they can be detected. Slightly to my surprise, the classic solution of putting a dab of resistive paint on the axle over the insulated wheel hub actually seems to work rather well, and only takes a few moments per axle.
One thing you discover very quickly is that the idea that you only need two wires for digital is a myth. Fortunately, I’m in a position to buy wire of the right colour and thickness nowadays, rather than scrounge around for whatever discarded bits and pieces I could find, as I did when I was younger. Something else that makes life a lot easier is a staple gun for pinning wires and cables to the underside of the layout.