I'm no pro, but if I recall correctly, I collected all wild pets so that I tried to hunt for a rare or at least uncommon in each zone. Especially if there were only 1-2 breeds of each pet, though I wasn't initially aware of breeds at all. If the pet wasn't spawning fast, I didn't bother farming them for hours just to get a rare. Sometimes if the pet had max 3 breeds I would just try to get one of each so that if there later was a need, I could potentially upgrade the pet.
On one hand, it's nice that the pet list isn't full of grey/white pets (I do have plenty of those too), but on the other hand if the pet in question has multiple breeds and you don't currently know a situation where you would need that pet, then it might be better to hunt for a rare or a specific breed once you know what you'll need. But that's a different point of view than the pov of someone who wants to create their own tactics and teams
Edit. Once I learned about breeds, I tried to check wowhead/warcraftpet comments about which breed might be useful, and then I tried to get those breeds just in case I would need them too one day.