While some may tout the DDR4 as better or a lot better, it really isn't so much 'better' as it is new. If you are talking a device with say a 6th-generation Intel CPU, then you are better off with the DDR4, but beyond that, and the fact that the 3 and the 4 can't work together, there isn't any serious difference. The DDR4 uses a minuscule less electricity, but not enough to have any effect in use of a plain laptop. Now if you were using it in say a server farm, then it would make a difference in the electrical usage.
So, in regard to just that one aspect, DDR3 vs DDR4, no it would not make any real difference for you.
Now in the future, more devices will be using the DDR4, but cost wise, now, it really isn't worth the difference.