It depends on your taste in music and hearing really Andy
Sorry to point the obvious out but you need to demo them both if you can.
They are both very good mini-systems and the Q Acoustic speakers are very good too but the Denon system will sound better to others over the NAD system and vice versa.
Have you a total budget in mind and does this include a budget for the likes of speaker stands and speaker cable?
If you are looking at the NAD money, you could also look at the TEAC I've got.- and you will also get wireless/wired streaming and internet radio,plus phono input if you have vinyl.