The major storage and circulatory form of vitamin D is:-
Cholecalciferol is first hydroxylated at 25th position to 25-hydroxycholecalciferol (25-OH o3) bv a specific hydroxylase present in  liver. 25-OH D3 is the major storage and circulatory form of vitamin D.
Reference: Satyanarayana- Biochemistry, 3rd edition, pg-125
25-hydroxycholecalciferol
1,25-dihydroxycholecalciferol
Cholecalciferol
Calcitriol