Wideband is definitely one of the more useful ones. EGT is useful too. It changes instantly, so any sudden increase or drop in temperature spells trouble, such as a clogged injector on it's way out.....but then again that manifests itself as misfiring.
I had waaaaaay too much info in my VR6 turbo. EGT, wideband, oil pressure, Volts, Amps, boost, oil temp, injector duty, coolant temp, water injection flow rate, chargecooler flow rate......everything. I spent too much watching this stuff and not really focusing on the road, or focusing on driving enjoyment. Plus the wiring was a pain. Ripped it all out apart from wideband and EGT and enjoyed the car much more.