The comprehensive answer to this would look more like that novel "War and Peace" but... I use a radial scan. The way I use it is somewhat dependent on what I'm trying to achieve at the time.
In S+L cruise, my standard scan goes from AI to ASI and back to AI. Then to DI and back to AI - and so on right around the panel. Always a good idea to include engine gauges from time to time as well plus, obviously, your navigation instruments.
For other stages of flight, different instruments tend to assume more importance. I suggest that you think about what you're trying to achieve in a climb or climbing turn, in a level turn, in a descent or descending turn, etc. If you think about that for long enough, it soon becomes obvious as to which instruments will tell you more than others.
There's a logic to it all.