We use and love Purex – I decided to give it a try once when we were running low on funds and I just couldn’t afford the Dreft…turned out to be a blessing in disguise! It costs less than half of what the Dreft sells for, gets things clean (even our seven year old child’s clothes, which we mix with the baby’s at times), smells good, and does not break either of our children's skin out, who both tend to get dry patches. Our first child is no longer a baby, but still has sensitive skin. She is fine with her clothes washed in our regular brand now, which is Arm & Hammer, or the Purex. However, I use detergent on her clothes only if they are being combined with a load of ours or the baby’s; in both cases I use the detergent only for the scent (the smell of the Purex seems to be a comfort, and my hubby likes the smell the A&H has too). However, I don't need hardly any of either, which I will tell you more about why that is the case here in a second. In short, Purex is what I personally recommend, from my own experience.
I have never heard of laundry detergent causing SIDS, so I cannot speak to that. However, it could be that too many perfumes aggravate breathing perhaps...??? That is just me thinking out loud - it's all I can think of that would make any sense. And if that is the case, Dreft would seem to be harmful as well, since it also has fragrance on the ingredient list.
Okay, so back to why I don’t use much detergent: Detergent isn't necessary at all in my case b/c we purchased a unit called a Laundry Pure. It requires no detergents at all; it oxygenates the water to get the clothes clean - so they last a whole lot longer, don't fade as much, and don't bleed (yes, you can mix all colors!). It uses a UV bulb and a silver probe, which come with the unit and lasts for about 750-800 loads. Replacements are easily purchased online for about $80 for both. It runs on the cold water supply only (saves money on hot water, which isn’t necessary either), but you can still use the hot water – it just won’t go through the LP. So what I like to do is run the baby’s load with hot water and Purex, and then run them again with cold water/LP. Since her loads are often small, it ends up using about the same amount of water as one of our large loads. We have an older model W/D set – we’ve had it for @ 15 years, and we’ve had the LP for about five – so I’m not sure if it’s helped, but it is supposed to lengthen the life of your W/D since it keeps it cleaner and uses no chemicals. I believe they make one for HE washers now as well. They keep themselves clean too, so there is no maintenance at all (except the light & probe every so often – when the indicator light comes on – we’ve changed ours once in the five years we’ve had it). So, we could quit buying detergent altogether if we wanted, which is nice when we are running low; it's not a crisis. If you want info on how to buy a Laundry Pure, just let me know - I'm sure I can dig it up. They are a bit pricy, but well worth it in the long run.
Anyway, good luck - and don't hesitate to ask for more info on the LP if you need/want it :)!