Sorry to bump an incredibly old thread but I thought this was quite fitting at the moment seeing as I'm heavily into Lotus 3 again. (And anyway, a lot of newer members have probably never seen this thread...)
It's definitely my favourite game in the series; loads of options and tracks, and that bizarre track "editor", though for me I used to have loads of fun just typing in random words or friends' names in and seeing what tracks came out of it
I like Lotus 1 too, though I don't like playing half-screen in one-player mode. I'm not too keen on Lotus 2 I must admit, I can't quite put my finger on why; I don't think it's a bad game but maybe there's not quite as much to it as there is to number 3.