I think that this is a matter of personal preference, and software available to you. The software you are using, MS Visio is not bad.
You can also use a CAD software to design the circuit diagram. If a component is not already available from the library, draw it and save it in the CAD software's library for future use. You can obtain the circuit diagram from a Schematic/PCB design software like DesignSpark PCB, Proteus or Orcad. Or obtain circuit diagrams from simulation software you are using in your work, like for example PSCAD, Plecs or Matlab/Simulink (with the Plecs addon). Or a SPICE software like for example LTSpice. There are a lot of other similar software that you can use.
if you can spare some money, I suggest to use CorelDraw coupled with Latex plugins for the text/symbols .. the exported vector graphic in EPS/PDF format look very neat and professional.
Otherwise, Inkscape is a freeware which also produces reasonably good vector graphics ..
Various options are available. Choose a cloud option if you are frequently traveling or use multiple OS. Smart Draw is a good option and with Visio compatability.
For quality and simplicity, I would go for LATEX with its circuitikz library (http://www.texample.net/tikz/examples/tag/circuitikz/). TikzEdt that helps me drawing using tikz.
"google drawing" is simple to draw for small diagrams in power electronics, no need to download any software. we can draw on web page and directly they will be saved to google drive.
Microsoft Visio is best one for power electronics drawings and they are with high quality.