Hiya. First up, its great the protanks are hitting the spot for you. So it seems the next thing is about battery life and power perhaps?
Before getting into that, vapor production is mainly caused by the VG content of your juice. Changing the VG amount can make a very big difference to the amount of vapor produced. I know this from experience, and even going from PG/VG 70/30 to 50/50 made a big difference with my juices when I tried it. So if its just about vapor production, you may want to experiment with your juice VG level first.
With mods, its about battery life and power capability. I've found that I will have more vapor with more power generally, but overall its the VG content that is really causing the big increase in vapor. What variable regulation mods give me is a longer lasting power supply, a stable vape for longer, the opportunity to set the temperature and power of the vape to where I like it, and battery safety features such as low battery cut off.
A mechanical mod is dependent on the voltage of the battery and the ohms of the attachment. I can set that up how I like it, but can't regulate the power supply constantly. I need to check the battery with a voltmeter, and know the limits of the battery in amps as well.
I use both kinds of mods - variable regulation and mechanical. I don't think either by itself gives more vapor production. Next to VG content, the next biggest thing is the ohms of your coil and the power going to it, and there are a number of mods that work well.