I am currently training with Sheffield Aero Club and think it unlikely the statement "just trying to make up hours and are not really all that interested in the student" applies to them. I cannot comment on Phoenix.
As far as weather is concerned, I wouldn't worry too much. As eltonioni says, there are four runways to choose from and they're very well kept. The likelihood of cancellation is probably no greater than any of the other airfields in the region - grass or concrete.
As for the difference between the two clubs , you might be better dropping by for a quick natter. I find the SAC has a strong social element over and above the basic training. With that and the regular ground school sessions, I would happily make the same decision again.