I didn't think Dell actually made their monitors? I thought LG were the ones that manufactured Dells displays with it not actually being branded an LG?
I'm supprised you don't have dell on your list. I would deff say that they make some of the best monitors.
I know ViewSonic have speakers in some of their monitors, I'm not so sure Dell do, Dell are also very expensive, or in the U.K they are. I got my ViewSonic for £200 and Dell so a similar one for about £250! I've had an experience with a Samsung TV and I though it was alright, Phillips also have good value equipment, some of their monitors include speakers but that may only be the one I've used. Also have a look at Sony, the one my parents have is top notch.