Though I still prefer 2001-2004 era, 1995 is certainly a good suggestion, all liveries that year were likeable except for Footwork IMO. Jordan would go on to have a far better livery, but their 95 cars were pretty sweet even If I should have hated the scheme.

1989 is also a good shout because it had alot of variety, mainly because of the amount of cars on the grid. Pretty much all were likeable actually, especially Leyton House/March, Tyrrell, Onyx and Lotus as well as the predictable (Ferrari, Williams, Mclaren)

I must say though, the era in between '89 and '95 was a mixed era with alot of poor stuff in it, Lotus especially as well as Larrousse, Minardi (93-94), Jordan 92-94 (the addition of yellow in 1995 made a massive improvement IMO), Coloni, Fondmetal, Footwork etc. Mind you, post-91ish was when F1 was at it's weakest if you ask me, and poor liveries as many teams became desperate for sponsors was the unfortunate result.