If I had to choose some F1 cars to put in it, I'd have a few early 90esque cars - a V12 Ferrari, a V10 Renault and a V8 Ford powered car. No girly gearboxes (not even sequential), no girly electronics (actually, I think the 1990 Ferrari did have a few bits of girly electronics, but they kept going wrong so that's acceptable), no girly narrow tracks/grooved tyres, or power steering, or anything wussy like that. REAL racing cars.
Perhaps a range of 60s cars too, some with downforce, others without. Hell, I could live with a lot of F1 cars quite happily.
However, it won't change the fact that the newer, faster ones would be crap for online play. Anything newer than 69 is going to be too quick for the majority of LFS players in anything other than isolation.