All of these games follow the same basic pattern of story telling. You defeat a sinister group such as team magma (or aqua, depending on the game), as well as facing against some form of main rival. You then catch 'em all, collect eight gym badges and start off with a choice between three Pokémon. So in my opinion, they're all good. And despite how obviously repetitive they seem to be when I look at them, I can't stop playing them and each new one as they come out now. Of all of them I used to be quick to say Pokémon Gold was my favourite. I've certainly spent the most amount of hours on that one. But truth be told I think Pokémon Sapphire (/Ruby) were my all-time favourites before Heart Gold and Soul Silver. I did like the Hoenn region and all the simple adjustments to the game that were then, new. Such as the Pokémon storage system, being able to run for the first time etc.