This is easy, the G.I. Joe aircraft carrier I got when I was 6 or 7. In the end it wasn't a toy I used the most or the most fun, but the drama in getting the gift was incredible. I wanted this thing for months, and begged my mom to get it for me any chance I got. When she kept resisting, I pulled the Ralphie and decided I'll just ask Santa instead.
Well, that fat bastard even said this 7' long beast of a toy might not fit on his sleigh. I was devastated.
When Christmas morning finally came I accepted the fact I wasn't going to get it. But when I walked downstairs I noticed this gigantic wrapped box towering over all the other gifts. I literally jumped up, grabbed the wrapping on the top of the box, and tore it all off to reveal the coveted aircraft carrier. Needless to say I really don't remember anything else I got on that day.