I regard all pokemon very highly, whether they look good or whether they're strong, but this thread said "Starter", so my answer is Totodile, making my opinion clear regarding Feraligator's worth in the end of the game and Croconaw in the middle. The Aquatic Gator has a considerable offence, both magically and physically, the starter version is oh-so cute. (Feel free to disagree.)
Disclaimer: For those who have played both the original Gold/Silver AND HeartGold/SoulSilver, you'll know that the plot doesn't change that much, but the game improves by so much, am I right? (For those who don't know about HeartGold/SoulSilver, we'll respect you by not discussing it in depth in this thread.)