You can find this question here on Quora. Click here to see it
Thumb of rule related to plugins
1) I do not add plugins that have not been updated for more than 1 year. If my website have plugins that are older than 1 year I replace them with a updated wordpress plugin.
The top 5 would be
Akismet
Contact Form 7 One way to keep spammer from spamming your email box.
Really Simple CAPTCHA This keep those bot from sending you spamming email
Jetpack by WordPress.com–
Oh yes and Backup you don’t want to lose your hard work. Don’t you?
I will also add some of those plugins depending on what my clients needs
SEO WordPress SEO by Yoast
Email Marketing – Aweber, MailChimp for WordPress
Social Sites– Add Link to Facebook,
You can find this on