Best gift: SNES
When the SNES came out, electronics were still released in the US months before the Canadian release. Knowing how excited I was for this stupid thing, my folks drove down to the US to pick one up. I was the only kid in my hometown to have one for almost 2 months. It was awesome. I had no idea they went to get it, so I was running around the house like a madman when I opened it up. Managed to play Super Mario World for 12 hours straight (minus Christmas Dinner) that day.
Runner up: Lego monorail.
I realize that between the 5000+ piece Millenium Falcon, and robotics that can probably rival the mars rover, the space monorail pales in comparison. But hey, in the 80s this was pretty high-tech.
Worst gift: 5.1 speaker set
Not based on the gift itself, based on what a brat I was about it. I was more upset at the fact that I couldn't use them because I didn't have an amp to run them than excited that I was halfway to a seriously upgraded home theatre. It still upsets me that I was such a little prick about it.