My favorite pet is without a doubt Greater Sabretooth, it’s a bit weird that there are no difference between a normal and Greater version if they are decorated, only their name and hp value shows which is what.
I also like the Greater Bear, still not too big a pet and really great against mobs.
But as others have said thralls are the best fighters and deals a lot more damage than a pet, so I rarely ever use pets as followers unless I need cargo of heavy stuff.
I still have some Vathis the Heirophant in storage chest, 4-5 of them being a female version and while they have the highest hp I suspect they aren’t the best fighters…
I made a little test with the Black Rhino near Sepermeru where I killed all other predators around him and let some thralls fight him alone in Epic flawless heavy armor and a Legendary sword with upgraded damage.
Dalinsia Snowhunter managed to kill him and so did a Cimmerian Berserker, but Vathis the Heirophant didn’t make it despite having roughly 50% more hp.
On a side note: I have a boss croc trap with 8 level 3 Dafari archers, they could kill the boss croc in 4-5 minutes, but when I exchanged them with Votarie level 2/3 archers it took 10-15 minutes killing the croc boss.
I did the archer exchange around the new bow mechanics update, so that might have influenced the result, but it is definitely a lot slower now.
All these small tests may be coincidental, but it does make me wonder if high hp thralls not necessarily means better fighters.