I prefer to let the search engines worry whether a link is supposed to pass link juice or not. I've already given Google my fair share of information these days anyway.
Google isn't worried about your site. They will drop your ranking if they think that is for the greater good. If you are going to link without nofollow then you are trusting every site you link to never do anything that even vaguely looks spammy or like paid linking. If you link to a site that pays for some links (according to google's spam algos) then you will get 'panda slapped' and recovering from that is very hard.
Always use nofollow.