I’m not familiar with the Garmin equipment (we still have the original Raymarine ST60’s).
Last winter, we completely overhauled the electrical system on our Dufour 40 (2004). New batteries, battery isolators, re-cabling as needed, etc.
Not through any specic choice, we gravitated to Victron and, like Dave B, installed a Victron ‘Smart’ monitor at the chart table.
The Dufour instrument panel incorporates a volt meter, but the voltage drop is significant and that’s something you need to consider. Long lengths of cable, unless adequate in size, will give an incorrect (lower) read out of the actual voltage at the batteries. We made sure to use the largest multi-strand cable we could wiggle through from the batteries (in the aft cabin). (There are any number of websites that provide formulae to calculate V-drop, if you want to do the Maths).
A version of the Victron monitor does incorporate the facility to have a readout on your phone/PC. That, of course, assumes there is an adequate WiFi/mobile signal at your boat. (And, that facility will itself, draw a current).
I’m happy with the Victron monitor. It has lots of functions. But by default, I keep it on voltage readout and the little bar battery display gives instant guidance of the state of charge.