I think most of you are missing the point of the question - he wants to know which type is best of each variety of pet. As you can get several different spiders, several bears, etc. I think he wants to know which one of the spiders is best out of the other spiders. Which one of the bears is most powerful out of the other bears. Etc.
OP - I personally don't know as my ranger is still pretty newblet. My best advice is to open up the pet list "K" and, as Vayne suggested, write down the different stats of each type of bear (for instance) that you have. Then decide which one has the type of stats you prefer. OR if you don't have a lot of the pets yet, I'm sure you can find a pet stat list somewhere online if you Google it.
Heck, I didn't even know that different bears had different stats! lol That's news to me! heh For all I know they could all have the same stats. And if that's the case you just need to pick the one you like the looks of the most.
I use kettle (lynx) and stovepipe (jaguar) for their fast attacks, there is a link for all pets am not sure I am allowed to crate a link for them but look for liru's guide and in there is sycthrex guide to pets. It helped me tremendously with my ranger shortstop and she rolls through content.