A'rite cloud chaser. Welcome. It's tough to start out here without getting discouraged by EVERYTHING but these folks really care about you're safety. I'm going to make some assumptions because you're a "cloud chaser."
1) You already have a thorough understanding of ohms law. A Thorough understanding! Not how to plug numbers into an ohm calc, but actually what ohms law means, how it relates to V, Ohm, A and W, and also how they relate to each other.
2) You understand how different wire types, their gauges, coil sizes, etc relate to the heat flux of your impudence coil and also how all of that relates to ohms law. AND how all of that relates to making epik vapor.
3) You have the basic tools you need to make coils including A MULTIMETER/OHMMETER and how to use them correctly.
4) You know how Li batteries work, their dangers, and the specific limits (hard and soft) of the batteries that you own.
5) You understand the limits of your device and how to use it safely.
These are the BASICS. I hope you're asking what coil do we think gives the best performance on a 50w device (I.e iStick 50) because your question as worded made me worry about your safety.
Come back with questions and we will help you. It may not be the help you want but it'll be, hopefully, the help you need.
Cave