Easily easily easily the 1999 European Grand Prix. I don’t want to spoil it, but my god. The only race I’ve ever thought deserved 10/10 (I’ve never seen the whole of Suzuka 2005, before someone flames me).
The Hungary 2006 comments make me want to vomit, but I’ll keep it friendly. Although not a very interesting race, if you can find the 1996 Spanish Grand Prix you’ll see some great wet-weather driving there too.
The 2010 Canadian Grand Prix is also a must. I must say the 2008 Brazilian Grand Prix was quite a bore apart from the “will Hamilton get 5th?” aspect.
The 2007 European Grand Prix is always good for a laugh too. You can see why Alonso hates having to pass Massa ;-)
Oh and don’t forget the 2005 San Marino Grand Prix.