I liked Heartgold better honestly :3. I've loved Lugia ever since I first set my eyes upon it in the Pokemon Movie 2000, all those years ago buut Heartgold will still be my favourite <3. Reasons? As good as Lugia is, nothing compares to the beautiful Ho-oh. The bright feathers and colouring really appeals to me, I love it's soothing battle music and the storyline behind it. Stats are great,typing, just a wonderful version mascot in general :D.
Also HG in my opinion offers better Pokemon :P. Because it has Arcanine and therefore is the best game ever. I never played the originals so I can't say anything based on that, but to sum it up Heartgold is my pick :).