There are Eight professions altogether in Guild Wars two and here is the ranger profession pet choices you are given throughout the creation of your ranger.
I will try and keep each explanation Brief but keep in key info that will impact your build stat wise.
Ranger which is a pet class within Guild Wars 2, The weapon of choice is usually the bow. All rangers have a keen eye and steady hand for precision shots along with the use of nature to help them defeat the enemy.
There is a choice of pet from the following (dependant on race chosen). I have given a brief overview of what each pet can do but further details can be found at the end of the post.
Sylvari - Fern Hound can regenerate its own healing.and has above average Damage Per Second (DPS).
Human/Norn - Bear, this is a tank pet and can take a lot of damage whist in battle.
Sylvari - Moa can heal itself and allies and is a basic healer for you or your group.
Asura - Flamingo dishes out distractions using mainly interrupts.
Asura/Human/Sylvari/ Charr - Stalkers can dish out high damage but cannot take as much damage as the hound or Bear..
Asura/Charr/Human - The Drake family are your Area affect damage pet however it is mentioned that the salamander drake is difficult to keep alive as it does short bursts of offence but has few hit points.
Norn - Snow leopard is a tank pet however not quite as skilled as the bear but still a good pet to have.
Charr - Carrion Devourer can regenerate and uses dots of poison and venom to take down the enemy, can also retreat underground.
Norn - Alpine Wolf is used as a distraction and uses stuns and knock downs
Tank means that whatever it is has the most hit points before it will go down. If you plan on solo playing a tank is always the better option. At least that's how I play and I seem to do OK relying on a tank pet.