I too have personally had the best luck with 1.5 lbs - 2 lbs per week. The proper caloric deficit to achieve those weight loss amounts per week, along with a 25% carbohydrate, 47% protein, and 28% fat diet has allowed me to lose mostly fat with very little muscle.

With my body at least, it seems that the difference between 2 lbs per week and 3-4 lbs per week is huge in terms of how much muscle is kept during the fat loss process.

If you're already hugely overweight than of course it doesn't matter and fast weight loss should be expected.