Re: Raven or Bear ?
The sabertooth is for casual groups as it has the most AoE attacks by default. Just right click them so that they autofire all the time, set the pet to autoattack everything it sees, grab a tank who enjoys rushing from fight to fight, then jump in and wham, bam, the instance is over.
Only caveats, if your tank can't quite hold aggro, use the bear for the 10 second force taunt. If you're fighting dead things, use the raven for the Shadow damage mitigation as that's likely the type of damage they'll be tossing out (check the combat log, though, if it's all common damage go back to the sabertooth). In a casual group you'll be too busy feeding power, buffing/debuffing, and generally just dpsing to be micromanaging your pet, so grab the one that does the most damage to groups.
As a level 1 burglar, Bilbo got a pony when he joined the Smaug The Dragon raid. Then he asked for leadership, looted the chest, assigned himself the 1st age Arkenstone and mailed it to an alt (Bilbo's a VIP so can mail from anywhere). They did some PvMP and an Epic Battle, then he apologized and gave the Arkenstone back. He kept the pony.