Gauges or ScanGauge II or OBDII Wi-Fi or Bluetooth Readers?

I really like the Scan Gauge. Being able to mount and monitor from the dash is nice, although I just keep it on the dog house now since I can't get sticky velcro to stay stuck on our dash. I read the directions but had the Scan Gauage guy show me some tricks when I went to a GS Rally. I set the MPG and Avg MPG as choices, then alternate others.
Interesting the comments on Tow Haul--I thought the setting was for uphill driving or towing, not normal driving. I'll have to read more about transimission temps and Tow Haul.