They're both really great NAS's, my nod goes to the Synology as it seems to integrate slightly better with Macs (hidden folder defaults are more logical than QNAP)
The "j" version is the cheap and slower home version. If your business is small i.e. < 10 users then it's fine, else consider a non "j" version. You may also want to consider a RAID solution (at least three drives) just to be on the safe side. Remember RAID does not equal a backup and your backups should always be offsite.
If you have the bandwidth you can sync / backup folders between two NAS's over the internet.