For better or worse, laundry is in my bailiwick. This topic is discussed a lot on obsessive-compulsive DIY homeowner sites like GardenWeb. If you have an HE machine, I am not sure there is any realistic answer other than Tide HE. I've tried a bunch of other products over the years but the Tide seemed to perform the best and to cause the fewest over-sudsing mishaps. There are some overpriced European options but they don't really work any better.
We use different flavors for different tasks: Tide HE Free for clothes, regular Tide HE with a mild scent for towels, and Coldwater for, well, cold water.
Location: Live in Rockwall, TX but from da Wessbank brah
We kept having a problem with our towels having a milder odor. We used this stuff called "Smelly Towel" and it removed the milder odor. They also make "Smelly Washer" to clean the washer drum. We use it occassionally as well.