I have been throught Kaplan
program , the gains from this teaching varies according the instructors you have.
gives some kind of strong backgrounds.
for spotting wrong answer choices and mainly for verbal skills
However the quantitative part teaching is too broad and not specific .If your quantitative score is low I would recommend that you use it with Manhattan gmat
. those manhattan gmat guides
use OG exercises and refer to OG examples and practices
hope it would help
when there is a will there is a way