The T7i is the middle of the 7 series + T7, T7i, 77D.
The 80D is better built and partly weather sealed. The 77D is the replacement for the T6s from the 6 series. It is not really part of the xxD series, it is the top of the Rebel line.
If weather sealing and a stronger built body is not important than I would suggest the 77D over the T7i. More features and controls. Maybe they have a lot of T7i in stock or have a bit better profit margin.
If you can wait a while and save your money later this month Canon is announcing some new cameras including a rumored replacement for both the 80D and 7DII. Rumors are calling it the 90D. Prices for the 80Ds should drop.
What ever you do that 60D your are used to will make a nice backup or use it to teach photography to a family member.
Look here for a detailed comparison:
https://cameradecision.com/compare/Canon-EOS-80D-vs-Canon-EOS-Rebel-T7iThe T7i is a bit smaller, most won't notice it, a bit lighter but at the expense of build and weather sealing (it has none), it has the Digic 7 processor vs the Digic 6 in the 80D but most won't notice any difference. It's batteries don't last as long as the bigger 80D battery and you can get both Canon and third party battery grips for the 80D to double battery life and add portrait mode controls (no contortionist tricks to shoot portrait). It's sensor is a year newer and goes to higher ISO, but when have you shot at the 80Ds 16000 ISO let alone the T7i's 25600? The 80D has a brighter viewfinder, higher fps and higher shutter speed.
I own and use 5DIV, 7DII and 80D. My wife has a T6s.
The T7i is the middle of the 7 series + T7, T7i, ... (