No single favorite. But to name just a few (1) Yoast SEO (2) WP Rollback which is a plugin updater (3) TinyMCE Advanced (4) Login Lockdown which stops brute force attacks

yoast is a good guideline for SEO, esp if you are new to blogging.

akismet (which costs a bit of money) is totally worth it once you start getting more traffic.  It filters out most of the spam and will save you a ton of time.

Too many to count, and always re-evaluating to make sure doesn't affect page speed. 

Nathan Gesner - never used one, though this que stion was around recently.

Tough question as those I use typically have different but necessary functions. The one I am most thankful for is Akismet. I loathe spam comments!

OH man!  So many good ones out there, where do I start!?!????

• PrettyLinkLite: Think Bit.ly but with YOUR website address.
• Wordfense: Protection from hackers
• Disable Comments: Zero comment spam because no posts/pages/etc have comments enabled!
• Realbird: Need the pro subscription.  If your area uses Oodle a lot (mine does not) you can have a great search function.  For me, not so much.  Will likely delete it soon.
• Google Analytics Dashboard: Quick overview of your google analytics stats.
• All-In-One SEO: I like this one better than Yoast.  Yoast has an interesting feature where it grades the "SEO" ability of your blog post, but uses metrics that are not valid (according to SEO experts Nestor & Katerina Gasset)
• Social Media Widget: Allows for social media links in the footer.
• iQ Block Country: You need to download a free file every six months or so to get the most out of this plugin, but it blocks countries you don't want accessing the frontend and backend of your site.
• Optin Forms: Allows for people to subscribe to my MailChimp newsletter.
• Contact Forms 7: create forms for a multitude of purposes.

Those are all the general interest ones I use. 

IDX and Wordfence but there are so many good and necessary ones. 

beyond my paygrade!!! sad but true!

Wordfence - secures the site from hackers!!!!

I like Jet Pack because of it's functionality.

Why my IDX of course.

Not a Wordpress fan!

No idea.

I don't have one... of course, I don't use Wordpress...

Never used it, but someday maybe.

I do not have one.

SEO all in one plugin is my favorite WP plugin, Wordfence is second. I also really like Pretty Link. And my TCB plugin. 

I don't like Yoast at all. It even gives false SEO tasks to do. It gives you a failing red dot when you what you are supposed to do and I have a pet peeve about not getting all green lights:) That is just the top of the list of what I don't like about it. 

just as long as it works

Happy to see so many suggestions to check out!  I am relative new to WP.

I like the advice by Debbie Gartner