The largest and most visible swim suits at Trials was the Speedo FST II, Speedo is an official US Olympic team sponsor and thus had an inside advantage.
But surprisingly Nike had several make the team as did TYR.
I am not sure if amy other suit maker placed swimmers on the team.
The biggest talk in the stands was how the swimmers did NOT like the new Speedo suits. Most men staid away from the Speedo Fastskin II full body suit. Phelps would wear the full jammers, but did not wear the restrictive full body suit.
More men with full body suits wore the TRY, while Nike had several World Records set in their mens Jammer suits.