Which bird to feed?

The 98% seems to be too good to pass up, particularly if it has 15 ATK, which is unlikely with the 82% one. Going to level 30 is probably enough though.

It’s a cool bird but if you have another Raikou I would power up that one instead.

Definitely the 98%! The difference in the costs between level 15 and 22 is negligible compared to this.

The 98% one without a shadow of a doubt.

Even if the 82% one has 15 attack and the 98% doesn't