I've tried all of the web 2.0's you could think of. All had original content and most had at least 3/4 articles. In the end I had almost 80 sites. Anyway, after P3 hit, the site they were linking to bombed. Went from page 3 to page 15 or something, so I started to take my exact match anchor text off all of them and even removed my naked URL links from all but 3 of them...A weebly blog, a wordpress blog and a typepad blog - only chose these three because I checked their 'quality' in Majestic and OSE.
Anyway, it appears G have updated yet again this week and the site in question has moved up from page 10 (where it was hanging about) to the top of page 2 for 3 of my targeted key phrases. I have not put any new content on the site at all and done absolutely no more backlinking.
So, in answer to your question, I think any of the sites will work for you as long as you treat them like your money site, don't have too many (I'm now convinced G could see what I was doing with so many web 2.0 sites) and make sure they add value. Sites just throwing out content, even if it is original, may not work anymore unless you add something new to the party.
Not saying what I experienced is definitive but you can only go on your own experience can't you?