I use many plugins and my go-to ones are CookieMonster, Ghostery, FlashBlock, NoScript and RefControl. CookieMonster, Ghostery and Flashblock are easy to get used to, but NoScript and RefControl make an interesting pair.
Using these at first is incredibly painful. It is a true education how fragile the construction of some web sites is, with scripts and components coming from all over the place. Because you have to approve every cross site reference, separately to load and to execute scripts, you really get a feel for how cobbled-together some sites really are -- random CSSs loading from who knows where, scripts from google, trackers, CDNs, web design houses, software vendors -- a real dogs breakfast. It can be a challenge to work out how much actually has to run in order for the site to work, versus how much is analytics and advertising overheads.
As I type this, scripts from three different google tracking systems, as well as rpxnow and ooyala, whoever they are, are NOT running in my browser. But for some reason slashdot won't work without loading some junk from fsdn.com.