A verb for "be the most important"

Solution 1:

Try predominate:

to be the largest in number or the most important (Cambridge)

But I personally would go for a phrase made of two words:
take precedence

to be more important (than something else)

When it comes to making health care decisions, the patient's preference should take precedence. (M-W)

So your sentence would be:

... in both of which efficiency takes precedence.

It is understood that it takes precedence over all else.