It's a bit more of an even trade-off with Gold/Silver than it is with Red/Blue. Arcanine and Ariados (Gold) are generally superior to Ninetales and Ledian (Silver), but on the other hand, Skarmory and Donphan (Silver) are generally superior to Mantine and Ursaring (Gold). It's better to just get Crystal, though, which gets you all of the version exclusives except Vulpix and Mankey (neither of which are that useful).
As for Lugia vs Ho-Oh, Lugia's cooler, while Ho-Oh has a rarer typing and more immediately useful stat spread (Ho-Oh's built for offense, while Lugia's more defensive).