IMHO......
The absolute best washing device known to man is a long boar hair brush....yeah it's stiff when dry but when wet, it is softer than any cotton towel you could find & because of the tips only touching the paint, the swirl marks are almost 100% eliminated. Available at griots garage or Erie Brush & Manufacturing Corp, 860 W. Fletcher, Chicago (but you need to have a company name to purchase, no individual sales) .
The next best option, 100% cotton diaper (Babies r' us has em- about $20 for a bag). Doubled or tripled up, wash them 2-3 times with fabric softener before using them for washing & drying. For washing, without contact dirt on the vehicle, use the open butt of a garden hose, on low to apply water just ahead of the wash diaper....it almost makes the towel float and the remaining dirt float off the paint without touching.
Soap...I recommend: No7 Car Wash Concentrate
Available at Amazon, any True Value Hardware; Mfg by RainDance/ArmorAll Corp. It has been around for 40+ years, is a powder, very inexpensive and us about 1 tablespoon per 3 gallons. It also has anti-water spotting agents which until you try it the first time, you would not believe the advantage of drying a black car. (Note- BAF has a liquid car soap that many swear by as well including anti-water spotting agents- but I have not used this personally)
The one item to remember, although the boars hair brush is absolutely the softest, effective washing device IMHO, you still must periodically wash by hand as nothing replacing the cleaning of hand washing.