The first laundry detergent I tried was Earth Friendly Products ECOS powder. I found it at Meijer one day, and just decided to give it a shot. If I remember correctly, it was about $9 for the box. I had been using Tide liquid before, and I wasn't really sure about using a powder. I was pleasantly surprised, as it disolved readily and cleaned well. Since it was unscented, it didn't clash with my dryer sheets. Unfortunately, it also left some kind of residue on my clothes. After several washings, they started to feel a little... crunchy. I don't mean that my clothes literally crackled, but the did seem rather stiffer than they used to. I've since found that it may have been a reaction to the extremely hard water we have in this area.
Next I tried Seventh Generation's laundry powder, also found at Meijer. I don't recall the price, but it was more expensive than the ECOS. This detergent also cleaned well and had a fresh, citrusy scent. Unfortunately, it also made my clothes kind of stiff. Your mileage may vary.
I went back to using Tide for a while, but really felt guilty about it once we moved into the Prairie Box. We do a lot of laundry, and I was just imagining the cesspool clogging with soap bubbles...
Then I found Method detergent at Target. It's biodegradable, phosphate free, and smells very nice (I use "fresh air"). It also leave my clothes residue free. Oddly, the detergent doesn't make a lot of bubbles compared to Tide, but it cleans just as well. The price is comparable to "ordinary" detergents, but the bottle is smaller since it's a concentrated formula. The cap/measuring cup is about 1/3 the size of Tide's. The bigger bottle of Method costs about $12 and seems to last us about 3 months. I've also used the "free + clear" version with good results. Since I line dry some items, though, I prefer a scented detergent.
After liking Method detergent so much, I also bought the dryer sheets. I've read that these contain tallow, an animal byproduct, which upsets some folks (I'm not one of them). I'm not sure that they're biodegradable, but they smell great and leave my laundry static-free. Bach also likes them and will chew them up any chance he gets. Half a sheet seems sufficient for most of our loads of laundry, and the box contains 100. Cost: About $6.
I've also tried the softener-infused dryer cloths but don't like them nearly as much. They're more like wet wipes than traditional dryer sheets, and they need to stay moist. I'm not crazy about the scents. Two cloths were needed to kill the static in an average-sized load. Bach also did not approve and won't touch them. These cost about $5.50, less at Target than online, but there are fewer in the container (32).
I feel obligated to mention that I am not affiliated with any company or product mentioned, nor am I receiving any compensation for these mini-reviews. Just in case... :)