I hate Ruger large autos. I really do. I haven't had good experience with them, I don't like their feel, and I hate their looks.
I love Sigs, They make top grade guns, their actions are generally very smooth, and I haven't seen one yet I don't love.
That said, it's going to be your choice. There isn't enough functional advantage in accuracy, reliability, or quality to be of use to the use most people will put into their guns to make it worth mentioning. What matters most is this: Which do YOU like better? Which feels better in your hand? Which do you think looks best? Which has the best ergonomics to fit your carry style most comfortably? Those should be your determining factors. People on these boards can tell you THEIR experience, which invariably will make someone else will come along and contradict them, often call the other person names like poopy-pants or stinky-cheesehead, and tell you why the other person's wrong and dumb, but that advice is usually worth what you paid for it.
Useful things can come of discussions, like learning that a certain company may be recognized as having unusually slow or difficult customer service, or that a particular model may have a strength over another, but for the majority or top name handguns this is VERY slim. If the question is something like "Will my Ruger Mark I be a better gun than my Jennings?" there may be a little more uniform response, but like beatledog said, the two you mentioned are more like Ford/Chevy.
Of course even that can be a debateable item. Some people would say they won't buy Chevrolet since the government gave them money which Ford wouldn't take, but others will come along and say that it was justified to keep America strong. I mention this only to point out that this kind of debate exists in many areas of life, and it really comes down to:
Which do YOU want most?
Oh, and the Sig is the much better gun. ;-)
