Trader bias here. My conclusions come from a combination of trading revenue and prestige.

1. Trading Revenue
GS and JPM are usually tops but MS lacking.
( How Much Trading Revenues Do U.S. Banking Giants Rope In Each Quarter? -- Trefis )

2. Prestige
I know this may be a bad indicator. But it should still count for something.
MS is at 6. Barclays at 20.
( Vault.com|Best Commercial Banking and Financial Services companies to work for|Vault Banking 50 )

Okay, but Barclays better than MS in trading, I'll give you that.