you can get some neat rss readers with yahoo widgets or klipfolio
http://widgets.yahoo.com/
http://www.klipfolio.com/index.php?actio…
If by best you mean the simplest and quickest to load, then many free ones are available including one of my favourites, Abilon
http://www.softpedia.com/progDownload/Ab…
also others
Newzie
http://www.newzie.com/
GreatNews
http://www.curiostudio.com/
Nutshell (pretty cool)
http://nearlogic.com/nl/wp/?page_id=4
If you want loads of features and don't mind the odd crash and waiting ages for it to start up, you probably can't beat Omea RSS reader
http://www.jetbrains.com/omea/reader/
Note that if you're running Firefox, try Sage, Wizz or Fizzle; if you're running Internet Explorer, windows live toolbar has great rss reading functionality built into it. Also, the free browser Deepnet Explorer has a fantastic rss reader and is strangely underappreciated....
http://www.deepnetexplorer.com/