I have the same brand - Ridgid, and I use the crap out of mine too.
Kate
All of them leave scratches, it is just a matter of how small. Sanding is a method by which the scratches get smaller and smaller, until they are undetectable by the eye.
I think you should look at your price point, and what you are going to be using it for in the shop. Almost without fail, the more dough you cut loose with for a sander will get you a better sander.
But what sander fills the bill?
I have the 5" Ridgid brand (2 actually) that I use the crap out of. I use them for hard sanding, 80 grit planing, and the initial sanding for some projects. These sanders are beyond all belief at how sturdy the are. I have used one of these for about 4 years now, and it has sanded everything from house fascia for paint prep, metal surfaces to remove rust, and first sanding on table refinishing. Dust collection isn't bad, either.\
They are great value for he buck, and reliable to boot. At $70, I can't find another sander that is a better value. There is a thread floating around on another forum where one of the members even claims HD stands behind their warranty!
For finish sanding, I don't think you can go wrong with a great deal of the 6" sanders once you pass the $150 or so mark. There you change from a handgrip style to a more traditional sanding machine. I have a Bosch (actually so old it is a 5") that I love and have used for years. I have used the Bosh 6" and I was really pleased. At one time, Ridgid even had an entry in the 6" field that was made by Metabo for them in Germany. I think they are now made in China from the same tooling, but one of my cabinet shop buddies told me they were still good sanders. Loves that lifetime warranty, too.
But for me, my final finish sanding would be done with one of my half sheet sanders. I have the Milwaukee 1/2 sheet that I love. Finish - excellent. Dust collection - moderate. At $240 or so, it was expensive at the time, but worth every cent.
The other I have is a Bosch 1/2 sheet. It is about 3 years old and was Swiss made. Sadly, they no longer make this machine, but you can find them on ebay from time to time. Finish - excellent. Dust collection - perfect. It is the only half sheet sander I know that has about 20 holes in the paper that go through the pad. Exceptional when working indoors with dust collection. Bought this at CPO Bosch (although it was not a refurb) for $175 or so an never looked back.
For anything that will last, don't buy Skil, Black and Decker, GMT, or any other of that raft of low end Chinese crap. A good sander isn't that much more than a cheap one.
Robert