The DLP will likely be a bit better, but neither of those projectors is a home theater model, so they will all have their limitations over projectors designed from the ground up for home theater use.
The Samsung System? Which one? Generally speaking, there's a lot of information about any products you are looking to buy available, and the right time to ask if something is good would not fall on the day AFTER you buy it.
So, if you own it, and you can't return it, does it matter what anyone says?
If you can return it, and want more information, then I would actively persue that information in the audio section of these forums, and include the make and model number. Kind of like asking of my "Chevy" is any good. Hard to answer without the actual model number of the Chevy I own.
The projectors...
The Panasonic has been out of production for about five years now and with current projection technologies, could easily be bested by a sub $1,000 projector.
http://www.projectorcentral.com/Panasonic-PT-L730NTU.htm
The BenQ...
http://www.projectorcentral.com/BenQ-PB8250.htm
Is only a couple of years out of production, and includes the DVI connection. Unfortunately, it does not list or indicate HDCP compliance on this DVI connection, so there is no guarantee of any compatibility with HDMI enabled devices (regardless of buying any cables to make it fit). It still steps up as far better than the Panasonic, but it is a long ways away from being a excellent - or even a decent - home theater projector.