Well this is subjective. So your opinion of quality and mine are two different things. There are some guards that you listed that I would love to have on my team. The rest possibly not. Do all those listed have talent? Yes! But I wouldn't call all of them point guards that make their teammates better.
I'm not going to go through them one by one and get into endless arguments with whomever. Lets just say the I would list Paul, Williams, Harris, Rose, Rondo, Parker, Billups and maybe Nelson, who I think is a little overrated, as players I would to have running my team. In the second group, because of age I would list Nash, Kidd, and Miller, but knowing that their time is running out. Westbrook isn't really a point guard yet. He may eventually become one, but I wouldn't bet the house on it. I like Felton, but I wouldn't call him an upper tier point guard just yet. The rest are players that either, I simply don't like their game, or their too injury prone, or their too old.
Let me put it this way. If I had a free choice of this group of, Iverson, Kidd, Nash, Felton, Westbrook, Robinson, Davis, Arenas, Bibby, Ford, and Sessions. I would choose Sessions. Now I know a lot of people will think I'm crazy, and there's not doubt that perhaps some of these guys would have a more immediate impact on the team. But for the long term, I would prefer Sessions. Because thats how good I think he can be. The Kid is an assist machine, and more importantly, he hardly ever, ever turns the ball over. Something the Kings need.
Hey, I've been wrong as many times as I've been right. Well almost. Just my opinion..