Both are good, however they also require some time and effort to truly reap any long term rewards. Reddit over Digg is ideal for quick traffic, although the website is riddled with spammers, hackers and general trolls. One of the first Hub's I featured, a random one called "English Slang" did quite well there and is so far my most viewed, with 90% of the traffic from Reddit. I guess like many of those open page websites with a strong, yet mostly troll community. You will get a better result from topics which are funny more than factual. - Try posting in both their /r/WTF section and /r/Funny. Other than that the traffic is painfully low, if any comes at all.