I like Mineral-O (made by sticky tongue farms) for my vitamin free calcium powder.
I like Rep-Cal Herptivite or Repashy calcium plus for my vitamin powder.
If Im using repashy for vitamins, Ive got the D3 covered and dont need the calcium with D3. Otherwise, Mineral-I.
brand isnt all that important - what matters is understanding what is in the product you have, potency, and using it accordingly.