After living in Dallas (rock truck capital of the world) I had severe road rash. I decided to get both Dr. ColorChip Paint Chip Repair, dr. color chip, repair paint chips, touch-up paint, Doctor Color-Chip Paint Chip Repair
and LANGKA Complete Paint Chip Repair Kit: Repair scratches on your car without a professional paint job! touch-up paint, scratch repair kit, chip repair,
pics turned out terrible so you will just have to believe me.
The Dr Colorchip process is to cover the chips ( and you can be messy) with proprietary color matched paint, let dry for a few minutes, and wipe off extra paint with their paint removal liquid.
The Langka process is to use their paint prep solution to clean area, use OEM paint and cover the chips leaving blob but trying to minimize paint touch up paint over other paint. Let dry at least 2 hours and then use their paint removal cream (Blod eliminator) to remove the blob.
On comparison of the coverage of the paint chips (on close inspection), both covered the chips and the chips were a bit darker than the paint, but unnoticible from more than 3 feet.
The big difference is the ease of Dr. Colorchip. You can repair all the road rash in one setting in about 30 minutes with little elbow grease and great results. The Langka took a bit more work to remove, and the two hour + wait was a bit annoying. Also the Langka blob remover stinks to high heaven and I can't get the smell off my hands (I was an idiot and didn't wear gloves)
My recommendation is Dr. Colorchip based on the ease of use and equality of the repair. The AG price is about $20 difference, but you can get the basic product kit cheaper from the Dr. Colorchip website. The AG kit is the "Road Rash kit" and has twice the product. I cannot imagine needing all the paint in the road rash kit unless you're repainting the entire car.
Hope this is helpful in deciding on a product to use.