Al,
In my opinion, screw-in steps are the most difficult and most dangerous devices for climbing trees. Not only are they hard to screw into most trees, especially those with solid wood like oaks, but if you ever slip on a screw-in step, you most likely will gut yourself.
I far prefer strap-on steps to screw-ins. They're much easier to install. Using a climbing belt, you can set 10 strap-on steps in a matter of minutes. And they're legal everywhere. Screw-in steps are illegal on many public areas, and some landowners probably don't like them, either.
With all of that said, I far prefer climbing ladders and sticks to individual steps. My favorites might be the Rapid Rails. They're simply small, lightweight, aluminum ladders you secure to the tree with polypropylene rope. Quick, easy, and above all, safe. Three sections will easily get you 15 feet high. I don't have a current phone number for Nontypical Treestands, the company that made Rapid Rails. A company called Hunter's View makes a similar climbing ladder (www.huntersview.com). I'm sure many other companies do too.
The SwifTree by Summit is an excellent climbing stick. It has closed steps so you won't emasculate yourself if you slip, and you can grasp the central column for security as you climb (www.summitstands.com).
As a general statement, then, I would say the best way to climb is with climbing ladders and climbing sticks, not individual steps. Of course, climbing stands still have their place, and in our lodgepole pine/fir forests here in the West, I often use a climber over a fixed position stand. The Summit Bushmaster is a good one. Also, you can't beat the Lone Wolf (www.lonewolfstands.com). Ol' Man climbers are also excellent (www.olmantreestands.com).
One last thing -- use a climbing belt to install any climbing system. And when you get onto your stand platform, always wear a good safety harness.
Safe climbing.
Dwight Schuh