I like Kona solids. I've bought them at Hancocks of Paducah online, my LQS and Joanns. To me they are all the same. Easy to work with, but as mentioned, hard to tell right side from wrong side. I figure if I can't tell it doesn't matter.
I've also used Moda Bella solids and like them too. I've also bought them at Hancocks and the LQS. No difference there either.
Missouri Star Quilt Co. has a large inventory of Kona solids. Often they even have colors listed as out of stock on their website if you call and ask.