Actually, the careers of Romo & Rivers are very similar.... hence my initial comparison.
Why do you feel Rivers to be better than Romo?
I'd concede Romo as the better "athlete".
Rivers as the better leader
About equal in "arm" (which I feel is usually overrated)
Rivers better at managing a game
Rivers better at adapting to change
Rivers better in clutch moments
Since I am struggling to ever remember Romo winning anything important when absolutely necessary, I'd take Rivers over Romo for his ability to win clutch games.