you should chose nofollow but I think you want to get high PR so you need get more backlink from high pr site
NoFollow link are not helpful to get higher rank in the search engine list. NoFollow links are not harm your web site but at the same time it will not give any valuable result in the SERP.
Yes its true that nofollow links don't hurt you, you are not getting the value only no harm in getting a nofollow link
They can't hurt you for sure, but they will not do any on your rankings. However, you can use them to get indexed faster with a new site, from my experience.
They don't hurt you if you have a typical link footprint. They can help you get indexed more rapidly. However, if you only have nofollow links it might hurt you--especially if you get hundreds or thousands of nofollow links all at once. No follow tells Google, that the link isn't in being posted in a trusted manner. If that is the only type of link you have, it may trigger some type of spam filter because it isn't a natural linking pattern.
I find nofollow links quite helpful. They do help increase human traffic, and they actually hold some weight (very little) when determining your PR. Linkbuilding must be viewed as a natural process, having nofollow links is part of the natural process.
I just want to make a slight correction about "pagerank not let it leave a site/domain" as page rank is assigned to individual pages and not on the site or domain
It looks more natural to have both dofollow and nofollow links. If google starts some serious sniffing around your links and sees that they are all dofollow then .............?
And what will happen then? I would say - nothing. Of all the backlinks, only about 3% are nofollow. So even if you have no nofollow backlinks or 10% nofollow backlinks, probably nothing will happen.