Vajda had a solid career but nothing spectacular, with a highest ranking of 34.
Gilbert was actually pretty successful, he made it to 4th in the world and was a player that many of the top players hated playing due to his style of play.
Gilbert was a top-100 player in terms of talent but he hauled himself into the top four by being awkward to play. He would get into his opponent's head.
He wasn't great to watch. He was also motivated almost entirely by money. He made the end-of-year ATP finals 'final' once, but I think he tanked the match. The big showdown was with David Wheaton (now a preacher) in the semis. It was like a war, because they both knew $1m was at stake.
Gilbert won but said he had nothing left for the final vs Sampras, which he lost tamely. I think the semi was his final.