There are quite a number of “full-line” manufacturers, which offer (with some variances), subcompact, compact, midsize, and full-size cars; a sports car; a truck; a minivan/people carrier; a compact, small, midsize, and large SUV/Crossover; and at least one hybrid. Honda, Toyota, Ford, Chevrolet, Nissan, FCA (as a collective), etc.
However, there are brands that have a much smaller lineup, either due to popularity (like Mitsubishi), capacity (like Subaru), focus (like Mazda), or not fitting the brand’s portfolio or public perception (like Porsche, Ferrari, Lamborghini, McLaren, etc., etc.).
What brand is sorely lacking having several more models than they currently offer? I don’t mean they need the model bloat like GM has, but a few more models to “flesh out” the lineup.
My vote would be Subaru. Yes, they’ve had some ill-fated releases, due to poor timing (Baja and SVX), off-putting design (Tribeca), overpriced, or underwhelming (360, to an extent) But they have a legion of diehard followers - who can almost be as bad as apple cultists, and judging by the number of apple stickers on the backs of them, they share a good chunk of the same crowd), and there’s enough passion behind the brand - and perhaps now conquests from faltering brands like Volkswagen and Mitsubishi - to allow for more daring production vehicles, but without the questionable quality and design of vehicles like the Tribeca and Baja. The XV CrossTrek has been a success, despite being a lifted Impreza, and the Forester is a fairly good vehicle in its own right, so perhaps it's time for them to make a push again?