I have two TES moments I could consider favorites: The first was when I was explaining to my girlfriend where to go and what to do over the phone. It was her first time in Balmora and I said something to the effect of, "walk down the steps and turn left. Walk past the Argonian named Hul and hang a right. Walk to the narrow bit and head into the first of the dual buildings you see on your right -- that'll be the mages guild. Talk to Ranis Athrys and join," at which point she interrupted me and said, "Babe, you play this game waaaaaay too much."
The second is the entire beginning of Morrowind, from the opening cutscene to exiting the Census and Excise office. Nothing gets me going like creating a new character in Morrowind.