Mine was Bulbasaur.
I stuck with him all the way to the Elite Four, and managed to beat them all after a ton of training in Victory Road. I think my final team was Venasaur, Pidgeot, Nidoqueen(?), Butterfree, Beedrill(?), and Moltres. I'm not sure if Nidoqueen and Beedrill are right, seeing as how this was almost 8 years ago. I honestly have no idea how I managed to beat them, but I probably just used Moltres for the duration of the battles.
Now, Bulbasaur is my least favourite of the three starters. >_>
For my first Gold Version game, I used Cyndaquil. My first Ruby pokemon was Mudkip.