Why do you want 20-25 watts? Just about any coil you build, above the .5 the DNA requires, can be run in that range.
Do you want clouds of vapor or flavor?
Build a couple of coils and see what you like. You need to vape what you like not what I like.
The way you wick it will also have a big influence on how it vapes. You can use the same coil and rewick it and change just a little and have an entirely different experience with dry hits or gurgling.
I would use
Steam Engine | free vaping calculators to get the approximate dimensions and build a coil around 1 ohm and one around 1.5 ohms. See which you like. Try them at different wattages. Pick the one you like best and build one higher and one lower and see which of these 3 you like. Try different wire sizes and see if you have a preference.
It's a hobby and an art. There is no one coil. People are different and you need to find what you want. We can only give you places to start or look.