Really the only plugins i install on firefox are Web Developer, Firebug, and AdBlock. I can get an adblock-like addon for Safari, and I only use web developer and firebug when i’m developing. As a result, I end up using Safari all the time, except when I’m developing.
p.s. Safari doesn’t use ClearType (which is horrible), it uses some other engine (i’m not familiar with it, but here’s a link: http://webkit.org/blog/168/gdi-text-on-windows/ )
p.p.s. Sites looks better in safari than other browsers: http://macenstein.com/default/archives/1445