junglers have cds, mana ect. if my champ needs it more then you then i dont care im not giving it
IF jungler needs it more than your teammate. But that's a much bigger if than it would seem.
After first clear or second clear, junglers get 180% bonus MP5 from their item, amount a mage won't get even if they sacrifice damage and get Athene's. On top of that, very mana hungry junglers can get hunters potion. Moreover, mana regen from blue buff is percentage, so mana part is almost always stronger on your mage, if you have one.
AP part is also obviously much stronger on a champion that stacks AP, while there are AP junglers most of them only build moderate amount of AP, than going for tankiness or penetration.
CDR is generally strong on everyone, but than again, there are many AA oriented junglers, who don't need it that much at all.
If jungler is a Diana or Nid, and mid is Zed or Yasuo, or jungler is simply fed AF, than yeah, they will make better use of blue buff, but other than that buff is almost always better given away.
Red, though, is almost always better on jungler. It makes ganks deadlier and allows to take objective around the map more easily.