That is an um...interesting(?) list. One guy who threw more interceptions than touchdowns in his career, another who played in the 40s and 50s, a few guys who lost
a lot of games, and half the list is comprised of guys whose TD to Int ratio was worse than Favre's.
Everyone wants to forget about every other stat Favre has put up and only look at the interceptions. It seems like when it comes to Favre everyone throws out the MVPs, total and come from behind wins, playoff performances, etc... and only look at the interceptions. Seems like a double standard imo.
As far as him throwing more interceptions than touchdowns, that happened 3 times:
1993: 2nd season as a starter (definitely not his "prime")
1999: A bad season that was not helped by a total lack of a running game and a terrible defense
2005: He was 36, definitely not what one would consider a prime year for athletics, and the team was just down right bad.
Only one of those seasons could be considered in his prime.
At 38 years old he led a team that was 4-12 the year before to 8-4 before tearing a muscle in his arm and finishing 9-7
Something else to think about. Consider all the wins he had and records he put up as a passer. Now consider how succesful he was when he lacked a running game for much of his career. From 1992-2008 he played on a team that was in the top 10 in rushing 3 times, in the top 15 an additional 2 times, and 20th or worse 10 times. He had some really good defenses early in his career, but from 1999 on his defenses had an average ranking of 16th in the NFL.
One last very interesting fact. Of your top 10 the only QBs who go further between interceptions (pass attempts) are Montana, marino, Brady and Manning.
The only one of the comparable QBs you gave who did that was Steve Young.