A 50W mod that goes down to .2ohms (which most I would consider buying seem to handle just fine) will pretty much handle any pre-built coil out there and leave you very well set up handle any RTA, RDA on the market and get a good vape out of it.
Your only real limitation will be wire gauge, with 50W you're looking at tight limitations on dual coil builds with thicker gauge wires like #24, a fair bit of play with #26 and you can pretty much build whatever you want with #28 to #32 single or dual.
My day to day vapes while out and about range from 9W to 13W on my Kayfuns to between 20W and 30W on my Krakens, Orchids and Atlantis toppers, even most of my dripper builds max out at under 30W. I build for flavor first almost every time.
Sure I've got some builds that go way past 40W, but it has nothing to do with getting a better vape, those builds are high VG cloud builds purely for fun around the house and driving the wife crazy allowing me to enjoy two hobbies at once.