To be honest I largely disagree. Yes, if you find a truely reputable indie dealer but there are very, very few of these. Most of them know little about the cars, offer warranties that are worthless and know only how to stitch customers up and palm off tarted up cars. I hate this middle area of the car market with a passion.
Private seller - where you know EXACTLY what you are getting - or a main dealer, where at least you get a good warranty (But still need to go over the car with a fine toothcomb before buying!).