For the next patch? For 9.1.5, which is on the PTR now?
There is one change announced for 9.1.5, which is that Yellow and Green levelling stones will become more effective at lower levels. A Yellow stone will level a pet from Level 1 to Level 2 today. In 9.1.5, it will bring the pet to Level 8. Instead of granting the pet 1 level, it will grant it 2000 XP. So instead of needing 25 Yellow stones to get a pet from 1 to 25, you can do it with 12. Greens will scale the same way.
The bigger news from 9.1.5 is that pet levelling through battles wukk be 50% faster outside Pet Week, with an even biggerr buff to wild battles. It will stay the same during Pet Week.
I have a post with my thoughts about the changes here
https://eu.forums.blizzard.com/en/wow/t ... -xp/313978
It is possible, I suppose, that the cost of Yellow or Purple stones in Charms will also change with the patch, but no announcement about that yet. If you were planning to buy a truckload of Yellow stones, this would be a good time to keep an eye on news from the PTR.
But I see no reason to change your plans about anything else because of these changes.
If you are a new battler, the pets to prioritise are, as always, the ones you need to complete battles, but you seem to be far past that beginner state, so I don't see any need foryou to do anything special.