Why did I choose a mechanical mod? Value... reliability and performance at low cost. I am an electronics guy so I am aware of battery risks, safety, etc. This is not really hard... at all. I need money to pay for my kids more than I need to vape, so I have serious budget constraints.
Hcigar clone of Sentinel M16 mod: $35
Hcigar clone of Kayfun 3.1: $50
Battery charger: $10
18650 batteries (qty 3): $30
Kanthal A1 resistance wire, 100 ft: $8
Cotton balls, organic (lifetime supply of wick): $3
total investment: $136
I experimented with microcoils at 2.0, 1.8, 1.6, 1.4, and 1.2 ohms... ultimately decided that 1.6 ohms in my Kayfun clone gave me the vape I wanted with the juice I liked. It has been flawless. The so-called "mod" is just a battery case. I could make one that works with the junk in my workbench area if I had to, but $35 for a mech mod is much cheaper to me than a couple hours of my time to make one. I have no need for the unit to tell me ohms, watts or anything like that because I routinely use multimeters I can do simple math effortlessly (differential equations take more time and effort). I can keep my switch locked when the mod is not in use or take the battery out if I want to be really safe... In fact, all I need is for the mod (battery case) to house my battery and for my switch to reliably apply voltage to my coil on demand.
I have tried many other e-cig setups (BLU, ego c-twist, cartomizers, RBAs, leaky RTAs, etc.) before I decided to get my own, and many were plagued with problems I didn't want to deal with (short battery life, cartos dead out of the box, etc.)... many were more expensive than liked... and others didn't deliver the quality (flavor, vapor production, throat hit, etc) that I was looking for.
Mech mod + kayfun = me happy and not using tobacco.