While rather expensive, the Lenz Gold Mini is my decoder of choice, because of the features and configurability. It features railcom (which could become useful at some point in time ;)) and more importantly, it allows you to connect an additional power supply, which allows a locomotive to continue running for several seconds without getting track power. A very nice possibility to have in any scale, but especially the smaller scales.

I haven't experimented with the decoder heavily yet, so more info to come at a later point in time.