To be honest, as a Giro over Vuelta guy, I 100% have to side with
@Valv.Piti here. All these arguments like the Vuleta being the smallest GT, its spot in the calendar, the places willing to spend stages, all of that are really just bad excuses. To me it honestly feels like there has been a certain development in the Tour and the Vuelta where the organizers have really tried to improve their product by introducing new climbs, making fewer flat stages, going for more thoughtful mountain stage design, etc. Now I disagree with some developments to improve racing, like shortening mountain stages, putting steep ramps at the end of mtf's and those kind of things, but to me it honestly feels like some of these things at least had the right intention. The Giro meanwhile still seems to be in a state where the quality of the racing is completely secondary to the organizers.
I think by now the Giro is the GT with most sprint stages, with the worst designed mountain stages and the worst flow of the route. The only thing still sometimes bailing out the Giro routes is that Italy is so far and away superior in terms of potential climbs that it's practically impossible not to make a good stage design once in a while. Seriously, people are saying the Giro is naturally backloaded because all good climbs are in the Alps but I genuinely think if you completely scratch the Alps from Italy, what's left of the country would still be a better place to design a GT than Spain. Italy is that much better suited for mountain stages. I just wish this will change some time soon because it's honestly a travesty to see what the organizers are doing with what they have.