Getting FFVII, it was my first JRPG and had my parents not bought me the guide I doubt I'd ever have finished it. I used it the whole way through and it's still my favourite game ever.
Other highlights are my friend getting me in to pc gaming with Quake. Playing worms around Christmas 97 it was just perfect, playing command and conquer for the first time.
I also recall when he had his and his dad's pc networked so we spent the whole summer holidays playing unreal tournament, quake 2 rail only and various other games.
More recently was WOW, I'll never enjoy a game as much as I did that for the first 3 years. These days I'm lucky to enjoy a game enough to even finish it.
Too many in the past to mention any way,. I grew up in the SNES and PS era so I really think that was the best time.