Digg is used mostly by tech geeks, which doesn't suit the demographics of my sites, so I use Stumbleupon more.
If I had to chose; Stumbleupon. Because it generates much more traffic. Digg on the other hand generates less traffic but is much better for SEO purposes.
I'm personally a bigger fan of stumbleupon just because I like the setup better, but Digg is good too.
Good as a user experience? Or good for SEO? Or good to get traffic? SU is a better user experience (Digg has a narrow community of Apple and Kevin Rose fans, SU is easier to use) Digg is better for SEO (their links seem not to be NoFollow) SU gives better traffic, judging by my Google Analytics reports. OP: Why not also consider Reddit and del.icio.us also?
If we look at the poll, we can see that digg and StumbleUpon are at equality in terms of DP members' preferences...
i prefer to Stumble, But digg Is Better To Know Whats On Top Like Tech News Most Of The Time i dont Find very cool News On Stumble Upon, Stumble Is Good For Exploring new stuff For me
I have relied on digg mainly to give me good serps....at times better than even the direct links to my own posts! Regards, RightMan
Are there sites where you can promote/request people to digg or SU your site? I have a new blog site with a ton of blogs that I'm trying to get traffic to.... www.mikeinmind.com by the way! ha
Now, the thread's pool shows that Stumbleupon is liked more than Digg... I don't know why, but I think that Digg will have more votes than Stumbleupon in the near future