Keen Pittsburgh's are a very comfortable boot. I had a pair and really liked them. Little to know break in time, excellent cushion and just found the fit to be very good. The only problem is the mesh on the top, I do a fair amount of welding at work and ended up with slag burning holes in the top and getting a few burns on my foot. Other than that I would buy these boots again! I have to have an all leather boot to protect from sparks/slag so that's something you have to consider as well.
I spend 12 hours on concrete floors. I have tried red wing king toe lace ups but didn't care for them. I now have Irish Setter square toe pull ons. I love them very comfortable all day long. Warm and waterproof too