I think that all of the regular EC artists did great work back then. Each genre had it´s 2 or 3 top artists and they're best work was imo always confined to one genre, except for Wood who did his best stuff for the SF titles and Shock.
I can understand that Kamen is not a favorite, but I have always liked his art a lot. He was quite an expert in drawing faces, especially those of women, showing all the different moods his female characters would go through in a story really well. Another expert at this was Schaffenberger on Lois Lane a few years later.
Severin was imo one of the best EC War artists. I'm a huge fan of the WW 2 and Korean war stories he did with Elder. Nobody, except Davis was able to make those stories seem so real. They really managed to show what those soldiers went through when they were in the field, not having washed for days, some full of fear, advancing in the dirt towards their next battle...
But all the artists were great at EC, I just think that Kamen and Severin deserved a special mention.