After having experimented with it, I would say I lean towards the H/S breed being the most useful one out of the four breeds, as having a high base speed plays well with the unique abilities of the pet, Sand Bolt and Quicksand. Which will dramatically slow enemies, and if you have high base speed, it will very often allow the sandling to go first.
Only two options here: P/B and B/B, making it easy to choose the best of the two. I find it a pet best suited for buffing up with Caw, and hitting enemies with acidic goo. Then choosing Slicing Wind for the potential omg large critical hit. or for the less inclined to gamble, peck. But definitely a pet for those whom likes to take chances.
Son of Animus:
Finally aquired it today and it only comes in one flavor, power/power. Which plays well with its ability set. It can be quite tanky with extra plating + siphon anima or touch of the animus. The later seems to return 30-50% of the damage inflicted as life. But it only lasts for 2 rounds unlike the 5 rounds of plagued blood, though having a much higher health return. Personally im more in favor of siphon anima as its most immediate healing, and ive had it crit and return over 700 life. I think extra plating is the better of the slot 3 abilities, as its a 1400 hp pet, and the reduced damage taken helps it stay in the game longer to take advantage of its selfheals.
All 3 of them are unique looking pets with special abilities noone else have and a worthy addition to any pet stable.