From personal experience: the Tekonsha Prodigy P3 is hard to go past.
Whichever brake controller you settle on, make sure that:
1) It can mount somewhere that you can see the display, and activate the manual brake
2) It uses automatic calibration rather than manual (eg Tekonsha Voyager)
3) It is wired so that activation of the manual brake also activates the brake lights
4) Wiring is a minimum 1.4mm (6 sq mm) conductor
If you're going to tow over 2T, the NSW law requires that you also have a monitor installed to watch the breakaway brake controller battery and there's every chance that Qld and other states either have this law or will follow (along with another new one we're getting - mandatory reversing lights in new vans). This monitor needs to be somewhere that you can easily see, some people stick it to the inner part of the instrument panel, but I've mounted mine on top of the brake controller. My garage has a pic of the Tekonsha Voyager in position, which is now taken up by the Prodigy P3 and the RM6000 monitor.
