This is the same thing over and over again. Ultimately yes, an integrated approach normally makes a better essay. it is more difficult to do, but it makes for a more sophisticated answer. to take an integrated approach, you would choose a theme and compare them both in each. so for example, look at the values and attitudes.
For example:
in this speech there is a theme of democracy becuase of the etc etc context
HOWEVER in this speech, being of a postmodern context where metanarratives dont exist, democracy isnt a major theme.
HOWEVER having said that, a text by text approach can easily be done as well. the main purpose of an integrted response is to save you doubling up on themes if the speeches are similar.
ultimately, it comes down to what you are comfortable with. great responses can still be achieved using the text by text approach. i would try both ways and see which you can do best.