I'd say Cyborg. He can physically lift large, heavy items, and can physically run through objects without receiving any pain. He is one of the strongest characters next to Starfire.
Terra can only lift rock, and technically she wasn't strong until she was wearing Slade's suit, and Slade was the one who was fighting for her.

Cyborg is physically really strong, but Terra's powers can destroy entire cities. But she just stands there and moves her arms, so she probably doesn't have much physical strength. So I'd say it's kind of a tie.

Terra can do some pretty wicked shiz.

I agree with Chbftw!