I originally went with Cyndaquil, but that was back when I went with Fire Types. Now, I'm more inclined to run with either Water or Grass depending on the corresponding pokemon. For HGSS, I'll most likely go with Chikorita. Now that there's a more acceptable selection of moves available to it.
Funnily enough, I lost my Quilava to a cloning accident before it got the chance to evolve, so my friend graciously gave me a Meganium Clone, but I wasn't too keen on that from memory.