Mine would be 3 excellent ones from the PS1 era, coincidentally all of them were made by British studios which are now reduced to mere shadows of their former selves, as SCE Cambridge is now Guerrila Cambridge which was responsible for some casual shovelware for PS3 and some ports for PSVita such as LittleBigPlanet or that standalone Killzone spin-off. Psygnosis had been used to be SCE Liverpool before its closure in 2012 (all they were allowed to do was some lousy Formula One game, downloadable WipeOut game and a standalone WipeOut game for Vita). What a disgrace.
honorable mention: Overboard! (alt. title: Shipwreckers)
By the way, please don't mention 2nd party exclusives that were on Sony consoles. Only 1st party. And yes, Psygnosis was ACQUIRED by Sony in 1993 but the exclusive deals were different back then so that some of their games appeared on PC or even Saturn.