If this question were easy to answer, everybody would do so.
I think the answer depends on your own website. (google trust, domain age etc) For me, the key is that your backlink profile looks naturally to google. Nothing else.
Especially for new(er) websites you should start with low quality and just a added backlinks. No new website gets ten PR5 backlinks from authority sites within first year. No natural backlink profile => no serp changes on the long term.
The more google trust, more visitors etc your website has, the more you can concentrate on high quality backlinks. One good backlink in natural backlink profile will help more than 10 good backlinks in an unnatural bl profile.
Same regarding the number of backlinks. 100 new backlinks for a 1 week old website within first month will not help a lot. 100 new linking websites to an established website will surely increase the rankings.