There are some comments here that are sensible, but unfortunately a bunch of people talking about something that they clearly know diddly-squat about.
For starters, Google already stated last year that they will use no follow as a 'hint' for ranking purposes. That means it's quite likely that it will contribute towards ranking at least in some instances. Here is a link to an article on
Seach Engine Land stating that.
Even before that announcement, there have been a great many people who believed that no follow links could directly influence ranking, despite Google claims to the contrary previously. Why? Because anyone with any common sense in SEO does not take tips, advice, and comments from Google at face value.
At the end of the day, asking such a broad question is fairly pointless as it is patently not a black and white issue. It depends on a whole range of issues and should be assessed on a case by case basis. Some of the things to consider; your aims, the sites themselves, the cost (i.e value for money?), traffic, your existing link profile (current follow vs no follow etc). Plus potentially a whole heap of other things.
Broadly speaking, and with some exceptions, everything posted in this thread should be taken with a pinch of salt. Very little of it - especially the poll - can actually be considered useful and you are far better off looking to test this yourself if you want to draw any reliable conclusions.
Apologies to the handful of people who posted in this thread with useful and sensible comments. I just tire of the bullshit from users who have zero clue and simply want to rehash something they have read elsewhere on the internet.