I still say Lugia.
My Lugia in Gold has higher stats than Ho-Oh when they are both level 73. I didn't use anything on Lugia, and in fact, I used about 7 HP ups on Ho-Oh and his HP is STILL less than Lugia's. In GSC, there are no abilities or natures, so it doesn't have anything to do with either.
The rest of his stats are also higher than Ho-Oh's.
Although Ho-Oh can learn Solar Beam, Lugia can learn Thunder/Thunderbolt and Ice beam. Ho-Oh is dead against a rock attack, whereas Lugia could at least survive one. Although an ice attack on Ho-Oh wouldn't do much, an ice attack on Lugia wouldn't do much worse damage, either.
FTW, Lugia is better. I think.
Avatar: In memory of ieatwyverns <3
Thank you, Vasco <3