Taken Only from Cars I've seen race in the flesh:
1. Engine:2005 Mercedes FO110R V10 - SCREAMMMMMMMMMER!
2. Aero - 2005 Renault R25 for the aero bodywork, with bits of F2004 and and the Williams Walrus nose!
3. Tyres - 2004/2005 era michelins (they were better, admit it.)
4. Ground Effect - Never saw one race, Chapmans 88 was cool though.
5. Suspension - 2001 Arrows A22 - For its innovative twin keel
6. Livery - Any Toyota livery, very arty.
7. Drivers - Michael Schumacher, Mika Hakkinen and Fernando Alonso, best 3 drivers I have ever seen race.