I have an '07 H3x. I'm looking for a good diagnostic scanner. I'd prefer one that does multiple brands, but not averse to getting a brand-specific one. I have one of those $20 ODB2 thingies, but it's not very specific. Any recommendations?

 

I have had a Launch X431 CPR123 Scanner for a couple years, works well. When you receive it you have to link it to a computer (I did w/ my laptop) select a language and download the most recent vehicle update from their site to the device, then you are good to go. Scans Engine, Trans, ABS, SRS etc..... live streams and freeze frames ....
If they come out with future updates, you can install them as well. Covers all kinds of vehicle including Hummer under GM. I had an SRS issue and it tracked it down.

You can get them on ebay about $127 or cheaper if you are patient and want to bid instead of BIN.
https://www.ebay.com/itm/LAUNCH-X431-CRP123-OBD2-Diagnostic-Tool-Auto-Scanner-Engine-Transmission-ABS-SRS/112459347910?epid=623493218&hash=item1a2f1977c6:g: 5CkAAOSwJRxbLfva:rk:2f:1&frcectupt=true