Synolog is a very good choice, but I would definitely go for a 4 bay Synology, because trying to expand one with only 2 bays later usually ends up at Ricardo or Tutti. With a 4 bay Synology you pay a bit more initially, but they are much easier to expand and you don't have to remove any hard drives later if you want to expand the capacity. Also, with 4 drives, you can use smaller sizes and not lose so much space in RAID5. The DS420+ costs even more than a newer DS423+, but a DS418 would also suffice:

Synology DS423+ (0 TB)

Synology DS418