I know a very good one indeed!
It's little-known, but deserves more attention.http://signature.neflin.net/wowpets/pets.php
Overtype your character, realm and region, then watch the options unfold.
This came about when I was in a similar situation, and I posted here: http://eu.battle.net/wow/en/forum/topic/13987408877
Rufa kindly, and ingeniously, turned my idea into a working site.
It takes a minute to get your head around it, so let it sink in.
Start by looking at Similar Beasts.
You will see all of your Cats with Claw/Rake/Devour/Pounce/Screech/Prowl, Snakes with Bite/Hiss/Burrow/Poison Fang/Counterstrike/Vicious Fang, and so on.
The entries in Blue are the breeds you own.
Each of the columns represents, top to bottom, the ones with most Health, most Power, most Speed, as a Blue 25
. Your actual pet may be a green 6, but what the site shows is its potential when levelled and stoned.
So if you want the fastest snakes, you can see that S/S breeds of Rat Snake, Grove Viper, Rock Viper, Sidewinder, Temple Snake, Snake all have the same stats and 341 speed.
It has other features, like displaying Duplicate Pet/Breed combinations, and will list Missing pets, with their tooltip, as well.
It helped me sort out my collection when I was my total pets were getting high, and I was lost in a morass of rabbits and snakes (Why'd it have to be Snakes?
) with no idea what to level and what to release.
I'm grateful to Rufa for helping me with it, and I hope it may be useful to others.