Lindley will out airmail them all
I guess if you factor in playing time it's probably Lindley as the worst not the greatest but I would argue Rick McIvor was actually the worst. He was the classic Bidwill lowball move. The Cards had a playoff caliber team with the best offense in the NFL, but Bidwill kept McIvor, who I think was a rookie, as the backup QB to Lomax to save money. Neil was great until he got a shoulder injury, but the Cards were afraid to play McIvor because he was terrible only 4 attempts all year, 0-4. So they played Lomax with the injury, we lost several games because he simply wasn't healthy, and wound up missing the playoffs.
Then if you're like me you strongly suspect playing those games with that injury probably contributed to the hip injury that eventually ended Lomax's career too.