Best 4.5mm Ball Bullet (Steel or Lead, etc.) for Air Pistol

Hi everyone, I would like to ask about what is the *Best (steel or lead, etc.) Bullet Ball brand for your airgun.

Speaking of details;
1. 4.5mm caliber
2. For Co2 air pistol
3. Overall performance (rigidity, finishing, "friendliness" for your airgun)

Let me know your trusted choice as I'm thinking of resupplying soon!

Cheers