Leraning simple things is much easier than learning something hard because we don't make any effort. At the same time, learning difficult things or things you don't know about makes you smarter and more intelligent as a person but requires much more time and hard work. As for me, I would definitely prefer to study complicated forms and grammar in English because it might help me in future. Simple things can never make your personality rich, so my choice is to spend more time learning English but to be confident in my knowledge.