Agreed with John. General driving, oil pressure will be a better choice. Yes, you do have a dumby light that will give you a second at most of warning, but the gauge will give an overall picture of things. Pressure will drop to 20psi when things are warmed up properly, and increase past 100psi on cold starts when driving past 3000RPM. Not to mention it can show you if you have a leak or not. I'm currently seeing between 15-20psi at idle ---> I have a leak, as evident from the stains in the driveway.
Oil temp will be necessary for prolonged stress on the engine. Track days, long periods at higher RPMs, or just general desire to know (my case) are areas that the oil temp will be desired.
Or, just get a sandwich adapter and buy both gauges. You can never have too many gauges.