The problem with T3 and genisys is they were essentially remakes of T2 to a certain degree. Salvation was the only movie that stood out as being different in that respect but it seemed like skynet had determined that 1 T-600 per city was plenty to maintain the status quo..Salvation could have been decent but the whole movie just seemed like it was masses of empty spaces with barely anything to indicate what was going on.
The problem with Salvation as a story is they pinched some ideas and characters from the Dark Horse comics, but bodged everything else up. They should have just bought some of the Dark Horse Comics stories and used those. It's the usual problem of thinking that explosions and special effects are more important than stories and characters.