I started out with the less expensive tools, but found that they didn't last very long and I was always wanting more power or better performance. I pretty much just buy Bosch and Makita now. Lows has Bosch, Home Depot has Makita. If I don't need it right away, I buy from Amazon or I do a search after researching the exact model that I want.
After several failures with other brands, and pads that didn't last very long and trying to find replacements, I went with this one, or one just like it.
Bosch ROS20VSK 120-Volt Variable Speed Random Orbit Sander Kit - Amazon.com
I have an almost new DeWalt sitting on my shelf that has gone through three pads. I can get them online, but they only last for a short time and then the sand paper wont stick to them anymore. I've had the Bosch for a couple years now and haven't had to replace the pad yet. Lowes has replacement pads in stock for it, which was another reason to buy it, even though I havent needed it.
I only buy Norton sand paper, which is sold at Home Depot. Lowes has the Gator brand, but it's junk. If you ever try both, you will see a huge difference in how long they last. This is especially true with sanding belts. I will drive twice as far, spend the extra time and money to get Norton over any other brand that's available to me closer.
Ryobi is a beginner, bottom end brand. Porter Cable may have been a decent brand a dozen years ago, but it's now all made in China without any quality control. Even in their prime, it was a medium quality tool.
Eddie