I would stongly advice to buy the Onkyo set. I am not sure the speaker package is better, but the versatility of the Onkyo receiver is just so much better. With a set of decent speaker it will sound much better than the Samsung box
The Samsung system is so limited in what you can connect to it. If you at some time want to add a bluray player and connect that with proper digital sound, you'll be stuck with the Samsung. No HDMI input, no available digital surround audio connection......
With the Onkyo you have the option to upgrade your speakers. 3 HDMI input for Bluray/PS3/digital Sat-tuner etc.
I just bougth a (wife friendly) Sony box set to replace my old surround receiver and big JBL speakers. Boy what a dissapointment soundwise.... A bit better on connectivity than the Samsung, but all in all a dissapointment.
It all boils down to what you're happy with. If good sound and versatility is a priority - go with Onkyo.