The best social bookmarking website or websites for you to use will really depend on what you want to use it for, but there are some general principles to take into consideration that can help you to make the right choice.
The first thing that you need to decide is whether to go for one of the big general social bookmark sites or a smaller niche one. If you want something to browse through and find random stuff that you might not have thought of searching for specifically using Google or one of the other search engines then obviously a larger site with a broad range of different topics may be best for you – although if it is entertainment you are looking for then there are actually some niche entertainment bookmarking sites around, such as The Daily Satire, which only features links to funny web pages and with an even narrower emphasis on news, politics and current affairs related humor.
If you want to use these places to find specific useful information that you can rely on then perhaps you would be better off going for a niche site, or perhaps finding two or three niche sites that fit with the kind of information that you regularly need to find and which you enjoy using.
But the main reason that many people use services such as these is actually not to find content at all, but to promote their own – both to the members and users who will click the links that you submit and also to create links for SEO so that you can get a better, higher placement in the Google search results pages.
Niche sites are great for this too – particularly if you can find one that has a category which includes one of the keywords that you are targeting. And that niche need not be just the topic, it can also be the areas – finding a specifically USA or UK bookmarking services can help you to geo target your SEO for the USA or UK, for example.
If your main concern is SEO and link building then the other thing to look at is whether they offer dofollow or nofollow links. Social bookmarking websites which have been created using the Pligg content management system generally offer dofollow links, although often only from the ‘published’, or ‘popular’ pages and not the upcoming ones. In any case if you click ‘view source’ from your browser you can easily check whether the nofollow tag has been added to the links on any given webpage.