I use a Snap-On MTG2500. The MT2500 is similar, but more popular. You will need software cartridges suitable for the newest vehicle you're going to use it with, and the OBD-II connector and keys. The '2500 series support ended in 2009. Given the proper software cartridges and cables/adapters, you can use the '2500 from 1980 1/2--2009.
The Snap-On Solus, Solus Pro, Solus Ultra, and whatever else is in the Solus family are all newer than the '2500. Support for some of them has also ended. They'll be more-modern, but also more expensive.
OTC also has professional-grade scan tools. Some of them were sold with Mac or Matco branding off the "tool truck". OTC is a dirty word in my shop, owing to the way they've screwed me on a "lifetime" warranty claim. Ever since they got bought-out by Bosch, they've gone downhill.
The "official" GM tool would be the Tech II. I have no experience with them, except to know that they're actively being counterfeited by the Damned Communists. Beware.
There's a dozen brands of "consumer-grade" code readers and scan tools. Beware.
P.S. You're not setting the timing on a '97 5.7L. You're setting the cam sensor offset. Turning the distributor doesn't change the timing because the timing is determined by the crank sensor.