I have done side by side taste comparisons of all of our breeds. My wife's favorite eggs are from the Banty hens that lay white eggs. My favorite are the Marans with the Basque at a close 2nd. Many of our eggs customers do the taste tests too. Those that report back almost always either say they like them all or that they like the big brown (i.e. Marans) eggs the best.
We see meat spots in lots of our eggs. I kept a running log on the dry erase board for a while of what breed every egg I cracked open was from and if it had a meat spot or not. I found meet spots in the White Leghorn eggs, in the Basque eggs, in the Cream Legbars, eggs and in the Marans eggs. I even found meat spots in the store bought brown eggs during that time and those eggs are candled. The Marans eggs had meets spots in about 50% of the eggs, but most on them were so small that if you weren't watching for them they easily would be missed. I am guessing that if you culled hens that produced 100% of their eggs with meat spots and breed those that were less prone to it that you could effectively reduce it in your flock. It is something that I would consider working on 5-6 years down the road, but currently I am working on Egg Shape, Egg Size, and production rate. I guess I would rather have a correctly shaped egg with a meat spot than an incorrectly shaped one with out a meat spot. Everyone defines quality differently.