Between the iStick 100w, pair of Innokin Cool Fire IV Plus, and several 50w devices and in between Aspire and Freemax tanks which can handle quite a bit more wattage I have been all of them vaping the best at about 20-25-30w max for both series of Atlantis and Triton, Triton 2 tanks as well as 30-40w for the Freemax models while the original saw one flavor running at 70-80w.
I generally have finding the "sweet spots" as well as best battery time results keeping these devices at about 33% upto the 60% range as far as how the wattages are set. If you are looking for a hot vape and a good deal of cloud coverage then the RDA option is one route while you can still see vapor increased even at the 25-30w range.
With just new tanks as well as just out new flavors I tend to tweak things back and forth until finding the best range per flavor as well a PG/VG ratio, air flow, tank design, etc. The findings here have been that's not always the watts that make or break the deal.