Hi glen, I went for the garmin 50 or 80. About £80 or so, more than enough. Thing is, there just a tool, and they have their own opinions on the "best route" often as not I've stretched the route out myself and just use as a guide. Because it's mathematical, it will send you via say the m25 on a Friday, to save 5 minutes, when in reality you'd be stuffed. So often I flip to the map mode, without a route.
Phone maps just as good, until you loose the signal, and the map blanks out.