Hi lucky,
here are my thoughts, mainly based on views on the German market.
First of all (and strange enough), ALL cars are in the same price range of 34 to 39 Euros. Only exception are some Flys (40 to 42 Euros) and the vanquish cars (42 to 45€).
SCX: Agree with you, BUT, as said, no advantage in pricing here. SCX has the gift to get most of their shapes extremely well, especially the modern rally cars.
Fly: Hm, some of their newer realeases are disappointing. I mean not the qiuality, but the looks (BMW 320, GT40). Still some great efforts like the Saleen, although they seem to have somehow reached their limit: If tampoos for example are very small and go over edges, the quality is rather poor and falls way behind Scalextric.
Scalextric: Hm, mixed feelings. some fantastic looking cars (GT40, MG Lola) but I still feel they generally have shape problems. Some cars just don't look right. Great OOTB for magnet drivers, but very slow if you really want to race them.
carrera: can't agree. Ok, some cars still look toyish (Enzo, Carrera GT), but some (new Ferrari F1, Vintage Nascars) are great. When looking at a Charger, it IMO even looks better and more like the "real thing" than the Scalex TransAms.
Spirit: Trashy looking 512M, uninteresting Lola, but with the Reynard they seem to be on a good path.
Vanquish: All is said. However, I don't think their cars are looking THAT impressive. Big problems with the wheels.
Ninco: Great cars, but I think in the near future Ninco HAS to do something in the looks department. With more and more brands taking bit steps forward, Ninco slowly falls behind. Even their good and right looking cars (i.e. Pajero, Punto) are not more than average compared to other brands.
Revell: Agree
AutoArt: Only got the Subaru, but IMO simply THE best lloking car i have, although the car itself is totally unattractive. Really overwhelming paint job quality. The Murcielago pictures I've seen are also simply stunning.