Go with a variable voltage or variable wattage PV first. These have protective circuitry in them that will help prevent you blowing your face off. Also, being able to control the voltage/wattage is nice as you can dial in a very nice vape. Which one to get? Doesn't matter, because if you understand Ohm's law, you understand you are really buying the same thing; the only difference is if the voltage for a desired wattage is being calculated for you by the PV.
Mechanical mods are essentially a battery in a tube with a switch. Those who understand their battery's Amperage, Ohm's law, and how to combine that with a (safe) resistance is loved by some for its Spartan simplicity.
I would guess you are really talking about wanting to step up to a PV that takes batteries you can replace - instead of replacing the whole shebang. Get one with some smart electronics in it. They are much safer and frankly, easier to use.
Mechanical mods are essentially a battery in a tube with a switch. Those who understand their battery's Amperage, Ohm's law, and how to combine that with a (safe) resistance is loved by some for its Spartan simplicity.
I would guess you are really talking about wanting to step up to a PV that takes batteries you can replace - instead of replacing the whole shebang. Get one with some smart electronics in it. They are much safer and frankly, easier to use.