That model DElta came out in December as a competitor to the Rigid R4512. They are about the same class. The Delta has a better fence but is 60 pounds lighter and not as Solid. But different stands. The Rigid is a hybrid on a shop style dstand and the Delta a contractor saw on a movable stand. Both have riving blades. Longevity, both have all metal mechanisms, but the Delta uses a lot of aluminum in the bottom end. The Delta, even thought the fence is a nice T2 Beisemeyer, the guide rail is split into 2 pieces.
Some Delta owners are already having problems getting parts replacement parts for the Delta. The Delta has a 5 year guaranty.
The rigid is about the same price is steadier, more stable and solid. It's the same price, but is Lifetime warranteed. I usually do not have any problem getting parts from Rigid.
The Sears contractor saw is a lot lighter than both those. I would say the class is below those other 2 models, so hard to compare those together. You could talk down the price depending on it's condition. Those are very common. It's a 30 year old saw. So common, that there is lots of used parts still around. I know a few friends that got some of those free, without motors, just for hauling them off.
So what if it said "3hp max"... (You seem to be real focused in on that label) The key in that wording is "max" You could have probably upgraded it to a 3hp 220v motor, but I don't see that in their doc's. That big a motor in a light saw is going to make it jump from the torque when started. But those old contractor saws, you could hang about anything off the back of them... Because the motor hung off the back... so not as much a consideration space and fitting. Depending on how it was used and maintained... You would have to check it for wear and being true. Of course being 30 years old, it's not a new saw and there is no guaranty. Most people I heard that owned that saw, said they felt it was underpowered. Most of them where using thin-kerf blades on it, because of the lack of power, to help cut better. But if you want a project... If the mechanisms and trunions are in good shape, then you are just looking at the brushes. The bearings were of common sizes, so will be available from a bearing supply for about forever...
Depends what you are really looking for and your budget. You don't have your profile filled out so staying with a generic recommendation. If you lived in the northwest, I still have my Rockwell for sale. I'm in no hurry, but I should try harder to sell it.