Both are dangerous, if you are doing duplicate content or affiliate marketing with ads than panda is dangerous and if you are doing excessive or low quality link building than penguin update is dangerous
I too agree with Jackdent. Because both are dangerous. Both are hit your site in different reason but at the end your site goes down. And I don't think you judge from both which one is bad.
Penguin & panda are dangerous,depends on the which purpose you use,if you are using the duplicate content then panda is bad, or you are using the make for quality link building then penguin is bad.
Both are dangerous because both are created for different reasons such as "Panda" main work is to penalize duplicate content websites and "Penguin" penalize spamming links or low quality of links.
I love Google Panda and Penguin update because these are the name of quality. First one is related to contents that are part of onsite optimization and second one is related to links. Contents should be original and links should not be spam.
If you are doing the right thing, you shouldn't be afraid of these Google algorithm. Only those who have low quality websites that should be afraid of these two. They are very, very dangerous for you.