The biggest winner (IMHO) was Warren. She should slowly replace Sanders, with a few more performances like that, as the ideologue favored by the far-left and now appears viable to go deep into the primaries.
2. Harris scores points and helps herself by KOing Booker. In the world of identity politics, she is clearly the strongest Black candidate.
3. Castro had an excellent performance and will now be recognized by Democratic voters.
4. Biden got hurt somewhat but did not commit the unpardonable blunder. He avoided it, which makes this a win for him.
The biggest loser (IMHO) was Sanders. He didn't do badly, per se, but was overshadowed by Warren's stronger performance against lesser competition.
2. O'Rourke came across as out of his league. His Spanish was partially an attempt to knock out Castro, who admittingly does not speak Spanish fluently despite the Iberian name. It backfired. Castro's English proved infinitely superior.
3. Yang had to do something to move the dial and I don't believe he did much of anything.
4. Buttigieg did not perform badly but did not attack. Nice does not win primaries nor add to his polling numbers much.