I ran a '2500-series scan tool for ~20 years. There's nothing "wrong" with them for OBD-1 use, given the proper software cartridges. The MT2500 has zero graphing capability, the MTG2500 has two-channel, rudimentary graphing. In this era, graphing is almost essential.
But understand that the newest of them is now thirty years old, and they go back to 1988. Snap-On support for the '2500 series ended in 2009. No repairs, no updates. The only stuff you can get for them now are the parts and accessories that happen to fit the newer "Solus Legend" scan tools--vehicle adapters and some cables.
When my MTG2500 died, I went with a two-generations-newer Solus Pro. The Solus family, in order: Solus, Solus Pro, Solus Ultra, Solus Edge, and the current version, Solus Legend. I believe that only the Solus Edge and Solus Legend have current support--updates and repairs.
Be sure to get software new enough, and vehicle adapters for any vehicle you intend to repair. It'd be wise to look for a unit that comes with the informational DVDs or paper manuals.
There's at least four adapters for GM vehicles, although mostly only two are needed. GM1 plus a power adapter, and the OBD2 adapter with an assortment of "Personality Keys"; K-9 is common for GM, there's about 50 keys in all. GM2 is the older, 5-pin adapter, and GM3 is for ABS on select vehicles. I own a GM3, I've never used it. I have used the GM2, but not for about six years.
In short: A Snappy 2500-series scan tool would have to be VERY inexpensive, or VERY well-equipped before I'd buy one. If it's well-equipped with a lot of vehicle adapters, those adapters transfer to the newer scan tools in most cases.