Almost certainly the Orion test vehicle launched in 2014. Aside from missions with humans on board, vehicles returning to Earth from space have been small samples, film, dust, etc, all quite small, except for the space plane X-37, but that lands similar to the Space Shuttle. Orion is the largest of the vehicles that will have humans on board.
A previous answer shows the size comparisons, and it is pretty clear Orion is the largest and heaviest of all human landers, at least the part that lands back on Earth.
The Orion version that was launched wasn't a complete version, but still had a mass of about 9300 kg. The Orion that was launched, while certainly the largest to be recovered by payload, is less than the Crew Dragon Demo-2 mission, at 9616 kg. I don't have numbers for Starliner, but the total package is 13000 kg, so likely less when landed. The only other spacecraft that might be close are Apollo CSM and Soyuz. Soyuz's total mass when launched is 7150 kg, Apollo's CSM is 5557 kg. So it seems like Crew Dragon is a clear winner.