The 77D is a major jump over the T6i, most particularly the AF system. The same AF seems to be also used in the T7i and the 80D, but with a varying number of features made available.
If you can swing for the 80D, that is the body to get, although, a serious lens upgrade will give you the best improvement in your image quality.
I would return the Yungnuo lens, and get the Canon EF 50mm f/1.8 STM.
Major difference in quality, both image and build. The most common complaint about the Yungnuo lenses is that they are noisy, which means gears rubbing together that will eventually wear out fairly quickly. Lenses should last longer than camera bodies, not the other way around.
Also, if you use Canon’s DPP software, then you will NOT be able to apply lens correction. Canon’s DPP software only corrects for Canon lenses. If you do not shoot RAW, and process the images into JPEG, then I suggest that you start.
Buying one HIGH QUALITY lens is a much better path than buying 2-3 “good” lenses. Once you try a high quality lens, then you will understand what I mean. The Canon EF 50mm f/1.8 STM, which I linked above in the Refurb store, will give you some idea of what i am talking about.
What you have picked out from BB is a good package. But, before you begin making a heavy investment in high quality lenses, I suggest that you make a decision now as to whether or not you want EF or EF-S lenses. You currently own one EF consumer grade lens.
Generally, the EF lenses have better bodies than EF-S lenses. But, moat EF-S lenses tend to be newer designs than the consumer grade EF lenses, so that the EF-S lenses tend to have better image quality, most particularly the “STM” lenses.
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