I have both. For me, the Langka worked better. The dr colorchip is good for small chips but it will keep pulling the paint out of larger ones.
You can use the Langka just like dr c by smearing.
I got the dr colorchip because BMW had some us wide shortage of touch up paint awhile back.
2015 F34 328iX GT Glacier Silver
2011 E90 M3 Monte Carlo Blue
2004 E46 M3 Imola Red