"Top variant" refers to the highest or best option among a range of choices. It typically signifies the most advanced or superior version of a product, model, or option available. Full definition
This is among the two top variants of the model, and it has a good list of features. (cardekho.com)
The range topping variant gets goodies such as projector headlamps, automatic climate control, ambient lighting, cruise control, seven airbags and a whole lot more! (cardekho.com)
Vehicle stability control and hill start assist control are available only on the range topping variants. (auto.ndtv.com)