We all know that both Digg and Stumble are extremely popular, but for as webmaster, which of the two is the best for you to focus on?

Step 1: Find if Digg dig’s you!

Here is the thing… Digg tends to favors content of a certain variety. Whereas, StumbleUpon welcomes more variety. So, go to Digg.com and use the search feature and type in the main 3 keywords associated with your niche.
How many results were there? Have there been many front page successes in your industry?
If you answered NO to any of the above, then StumbleUpon is your winner.If you answered YES, then we move onto step 2.

Step 2: How New Is Your Site?

Here is the thing… StumbleUpon is generally much easier to get instant traffic from, whereas Digg can be hit and miss, and can take a lot of time to get the ball rolling. If your site is fairly new, or your traffic fairly low, I recommend starting with StumbleUpon.

Step 3: What Sort of Content Do You Have?

The type of site is also critical. Digg tends to favor humor, tech, breaking news, celebs, and gadgets. Whereas, StumbleUpon has a wider range, but is especially keen on photos and images. Both sites like list-based content, StumbleUpon has a slight preference for tutorials.
Still not sure which site is for you? Ok, let’s look at the traffic.

Step 4: How Much Traffic Can You Handle?

Both sites can deliver huge amounts of traffic, but StumbleUpon can generally get results quicker. Digg will give a HUGE burst of traffic, which will last less than a day, whereas StumbleUpon is more likely to give you traffic for days and often weeks at a time.

Would your server struggle with such a fast burst of Digg traffic ? If so, StumbleUpon may be for you.
So Which IS Best? The above is a guide to show you where you should focus your efforts, but it doesn’t really answer the question of “which is best?”. That is because there is no fixed answer. It will vary from person to person.
Let’s move onto the most important part…

Quality of Traffic

It is widely known that traffic from sites like these is nowhere near as targeted as paid traffic like AdWords.

That said, the quantity far outweighs it. That said, the quantity far outweighs it. So it is a numbers game. For example, 1,000 hits from StumbleUpon may be worth roughly the same as just 10 paid hits from Adwords, or 500 from Digg. But remember, it is FREE, and there are many other benefits to the traffic, such as branding, links, subscribers, fans, boosting your stats, getting comments and more.
If you are looking to sell your site in the near future, then StumbleUpon is your best bet, as it can inflate your stats greatly. If you are looking to build links, then Digg is by far the better choice. Stumble users tend to not stay on the site for very long, but a Digg user may comment, check out your other pages, link to you etc…

Summary

So with all the above in mind, are you any nearer to knowing which is best for you? If not, here are some additional thoughts from other people:

Additional Thoughts

Many webmasters are saying that DIGG is the best. Hobby bloggers prefer StumbleUpon. Stumble will likely give you more upfront traffic but the traffic you generate from Digg is a little more targeted. So, Digg has more long-term and financial benefit for you. Digg didn’t give me much traffic but with StumbleUpon I can see immediately the result. Digg can be great if you already have a lot of traffic or social networking buddies that can click of the “Digg it” button to promote your page. Having a good member base can also be useful if you can convince members or clients to encourage you by clicking on your button.

By Stumbling you get good amount of traffic but bounce rate is pretty high. If you want to do branding you can go for Stumble but if you want targeted audience then go for Digg.