I've made a list like this before.
I may or may not have just one preffered morph. Gorilla, Cape Buffalo, Black Panther, and Polar Bear are all good battle morphs. The Gorilla has hands, which is good. The Buffallo can barge through just about anything like a battering ram. The Black Panther is stealthy. The Bear has the most raw power between the four.
The Golden Eagle, Goose, Owl, and Pidgeon are all good bird morphs. The Eagle has power, the Owl is a good night flyer, the Goose is a good distance flyer, and the Pidgeon is good for blending in.
The Killer Whale, shark, Octopus, Giant Squid, and Crocodile are all good water morphs. The Killer Whale is an apex predator, the shark can breathe under water and can sense electric pulses, the Octopus is a good stealth morph, and the Giant Squid is an excellent deep sea morph. The crocodile is good as moving on land and water, which can be helpful when fighting at the shore.
A Bloodhound is an awesome tracking animal, and the Wolf can be used for distance when the Goose would be less practical. A Rhino could also be good when you want a tankish animal, but the Bufallo won't quite cut it. A Black Mamba would also be good as something that can get in a lot of places, moves fast, and has venom.