Tamiya's T-72 is the best, followed by the DML variants and a way distant third is the Esci/AMT/Ertl T-72/T-74 kits. Trumpeter makes a bad copy of the Tamiya T-72.
DML variants includes the Kirin reboxes like the Free Kuwaiti M-84 and the T-72M1 Lion of Babylon. Decent kits that look the part when completed.
I have all of the DML/Kirin variants as well as the Tamiya T-72 and both the Esci T-72 and T-74.
As far as the T-80 goes, only the DML variants and the Skif one. Skif's detail is lacking and rather heavy-handed. DML's is better here. Lindberg used to make a modern Soviet tank labeled as a T-80, but was based off of distant photos and supposition prior to the fall of the Soviet Union. Not a serious contender as a T-80 and long out-of-production.
I have all of the T-80 kits I've listed as well as the Matchbox/Revell 1/72 scale T-80. That is a decent enough kit if you get the Eduard PE for it.