if you want a high quantity low quality display go with the dell and you will get a display that was made just to compete with other manufacturers. if you go with the dell you will get everything one would expect from dell, a lot of cut corners and an inferior product.
but if you go with the cinema display you will get a good quality product that you know you can trust. apple uses quality products meant to last. Just ask anyone with an apple display and they will tell you that they wouldn't trade it for anything, especialy a dell.