I have been using Ernie Ball strings exclusively for 20 years, and the past 2 years I've become an addict of the "cobalt" strings.
Unfortunately, Thomann don't sell the 10-52's anymore which is the gauge I use the most so I had to look for another brand.
Since D'addario's have a very good reputation and are widely used by many guitarists I thought I should give a shot at trying them.
Unsurprisingly the quality is very good, you can definitely feel these are top quality strings and not cheap ones.
Unfortunately, when it comes to the sound, I was quite disappointed.
Not that they sound bad or anything, but I really like my strings to sound bright and cutting (used to Ernie Ball cobalts), and the D'addarios sound much warmer and mellower. It might be great for some people, but it's really too mellow for me especially for a brand new set of strings, I didn't get that "sparkle" I was expecting.