It depends what you're looking for - if you're looking for SEO benefit then go after all of them, but in terms of a good bookmarking service for keeping track of your URLs i'd look at Delicious.
I never use such automated tools to bookmark my pages/sites. However, i manually bookmark my pages with addthis social bookmarking tool.
I have a great list of favorite social bookmarking sites, but i like most Digg, Delicious, stumbleupon, Tumbir, Identi.ca, friendfeed and reddit.
i will not trusting on any tool or website to submit my content automatically because Stumbleupon , digg , delicious , corank, there some reputed website from there we can get nice benefit of ranking and traffic so i just prefer to do manual...
Hi Friend According to me best social bookmarking website is cloudy tag,stumble upon. Regards : lacoste perfume