S&S;

...it's not as simple as "better or worse"...this is a matter of philosophical discussion and personal preference, and I do have mine...because the two instrument do indicate somewhat different things happening in the Elec Sys ...but I will present this as objectively as I can, so you can decide for yourself.

Ampmeter indicates Charge/Discharge Battery current (which is important to me and I want to know it more than Voltage, because it is the electrical reserve of the vehicle, and 100% to 0% charge condition happens within 0.8 tenths of a Volt, so a Voltmeter doesn't display this very well). An minor disadvantage is that typical Ampmeter wiring requires heavy wiring to instrument because large currents pass through instrument. Correct wiring should be per "H" diagram (See Reference)

Voltmeter indicates System Voltage (which is not not less important than Current, but less informative as Sys V gets pulled up or down as a function of state of charge of Battery and Loads. Also, there are other indicators of system voltage - Headlight brightness, Wiper/Blinker speed etc.). A minor advantage is that Voltmeter can be wired with small gauge wiring as only a small sensing current is used by indicator. Voltmeter can be connected just about anywhere in system because it draws so little current, but close to Battery is recommended.

(Reference: http://www.sw-em.com/elecramb.htm )

Bottom line is that a gauge is much better than an "Idiot Light" only, because it give us more info on the health of car's Elec sys...have fun deciding!

Cheers