Least cute: Gilda - she's not even a pony and worst attitude of any character on the show. Cutest: Fluttershy Best: Rarity.
Cutest: Pip. I mean come ON! What an adorable little colt! I just want to snuggle him right up! I love the CMCs, too. Silly fillies! Least Cute: Snips, Snails, and I definitely agree that Diamond Tiara and Silver Spoon need a serious attitude adjustment before they can be considered cute.
I dunno why some people think twist is not cute. But I find her one of the more cute ponies because of her lisp. But seriously Most cute: Fluttersh-HHHHHHHNNNNNNGGGG Least cute-Snails
Cutest: Fluttershy and Applebloom (c'mon guys, just listen to that accent) Least Cute: Snips and Snails
Tom is Pretty cute. He rocks! *badum-tss* :3 Snibs and Snails though... Not so much. :S Cutest is... Well, Everypony is cute in their own way. >.> Fluttershy is adorable, Applejack has dat accent, Twilight Sparkle is... Well, Cute in a Twilight Sparkle way. etc.
Those ponies in Canterlot that were mean to Rarity when they found out she was was from Ponyville. And the guy you was the window washer in Sweet and Elite. o-0