I prefer the Nano. It is smaller than the Single, has more memory available for the user because the partition for alternate OS has been deleted. Has a 12v external PSU. It is faster than the Single.
You will only have 2 USB ports, there is no scart but has composite. The HDD attachment is optional, but cheaper to buy at time of purchase if you could change your mind about not recording. It does not have a fan, does not need it unless there is a HDD. In any case, some people have complained about the fans becoming too loud.