There are pros & cons to running each kind.
Mechanical oil gauge is what I use, Sun makes a 270 deg sweep oil pressure gauge.
I run an electric water temp. the reason being, if it were mechanical, one would have to drill a large hole for the threaded fitting of the Bourdon tube to fit through the firewall. Plus, secondly, if you ever overheat your engine greatly, as in peg the meter hot, the gauge is broke.
If I want to know the temp of engine is when I have the hood open, I look at the thermometer I have installed on the crossover of the manifold. You can buy the two-inch dia dial with a short 1 1/2 inch probe from the local A/C supplier, has 3/8 NPT. Works great!