Since I know they can all be really good battlers, I'll judge them based on the way the Pokemon looks like.
My Top 5 favorite in order:
• 01 - Oshawott - my favorite of all starters and for my love of otters too. Its evolved form is my #1 favorite.
• 02 - Snivy - thanks to the anime, learned to love Snivy, especially Servine.
• 03 - Tepig - once again thanks to the anime, and since its from Unova, are my main reasons for liking him alot
• 04 - Cyndaquil - mostly for Quilava and Typhlosion (I learned to like them)
• 05 - Turtwig - only favorite starter from Sinnoh, and I like Grottle and Torterra's design a bit
(if I included the future 6th gen then Chespin would be 3rd - what ever its based on, its cute)
My least 5 favorite in order
05 - Totodile - I don't like reptiles much, and that 'happy-dancing attitude' in the anime made it stay clear away from it.
04 - Charmander based on a reptile are my main reasons I don't like it. In the anime, Charizard being used a lot made it another reason i don't like it a lot. It took away the excitement I had for it during the first 3 seasons.
03 - Piplup - general design of Piplup and its evolutions, and the fact that I don't like penguins at all are the main reason its down.
02 - Torchic - design first (all evo's as well). Based on a chick (baby chicken) made it worst, and I belive that non of the 'baby Pokemon' shouldn't exist for battling. They are supposed to be cute not battles.
01 - Chikorita - its the general design of Chikorita's entire evolution that I dislike
(if I included the future 6th gen then Froakie would be at 2nd and Fennekin at 5th [in this order: 5th Fennekin, 4th Piplup, 3rd Torchic, 2nd Froakie, 1st Chikorita])
I was going to update this almost 5 hours ago, but I kept getting the "website offline" message.