I have Macbook Pro and am wondering if ad blockers work. And which ones are worth considering.

I use AdBlock and find that it works very well with Safari: https://getadblock.com/

I use adblock plus. It blocks all ads plus the ads at the beginning of YouTube videos and on other sites as well.

I also use it to get rid of the entire right side bar on FaceBook.

Unwanted flash movies is what makes me crazy.

So I use the less intrusive "Click to Display" (the evolution of Click to Flash). Instead of immediately playing Flash, it labels the window(s) where it appears with a gray oval with the word ( Flash ) in it. If you want to see it, click on the Oval.

I second Adblock Plus!

Many ads can get around ad blockers if you inadvertently downloaded some form of adware. Please see this Apple article:

Stop pop-up ads and adware in Safari - Apple Support

and this article on a third-party site:

http://www.thesafemac.com/arg/