Australia, New Zealand & the South Pacific - Which is better: Milford or Doubtful Sound?

I have rarely heard of the later and trips seem more expensive, is it better than Milford?

They are both very beautiful. Less touristed (crowded) at Doubtful Sound, which some of us appreciate.

Seeing the coachloads of people driving to Milford Sound really put us off going there so we opted for Doubtful Sound.
It was just our boat on the trip so it was very peaceful & gave us the chance to see the Dolphins & Fiordland Penguins up close.
Doubtful Sound is also a lot closer to Te Anau & you get to see Lake Manapouri & its power station as well.

Milford Sound is every bit as beautiful as Doubtful, before the buses arrive. If you drive your own car you can be there hours before the buses...in any case the many stops along the route are a must-see making your own car essential to do this trip right. But a big crowd at Milford is measured in dozens of people, just to put things into perspective! Even at its worst it is very special. Similar northern hemisphere places, like Niagara Falls, have a million times more commercial exploitation -- as a point of comparison.