In my opinion, the two items actually serve different purposes, I.E. The
Whale Tail is to get your boat on plane faster while the Trim Tabs are to
adjust the port to starboard list. This is especially helpful in a boat
where people can move about and change how the boat is riding. The trim
tabs can bring the bow of the boat down some also, but if yours is an I/O or
an outboard you can do that with the Trim/Tilt adjustment more efficiently.

Bringing the bow down with Trim Tabs on an inboard is often the only way to
do it since there are no other adjustments for that.

Don Dando