Now, the deal with HeartGold, any why everyone likes it, is because it's the newest game. Being that it has the best graphics, Meta Game, etc.
But in general, the G/S/C/HG/SS it not very good. Not very clear storyline, or tough battles. Only Team Rocket and the Elite Four (to an extent) are hard.
The games that really were the best were R/B/Y/FR/LG.
They had the best Storyline, Pokemon, after game(FR/LG), and Trainers(Gym Leaders, Trainers, etc.), being that it was the first Generation.