I was at a vape store in Lawrence Kansas yesterday, one of the guys working there said all casually "mechs are going out soon" I said "what do you mean?" he said they weren't selling, I just had to tell him that he is SO mistaken. This kid looked at me as if I had no clue - lol
He's somewhat right, though everyone will have their own personal preferences, but in general.. Mech mods first came about because there were no regulated devices that could really appropriately utilize a rebuildable dripping atomizer -- basically, there were no regulated devices on the market that could "chuck clouds". Mech mods were necessary to get bigger clouds because you'd need to go lower in resistance, and many (virtually
all) of the regulated devices on the market ~2 years ago weren't capable of firing much lower than 1.2 ohms, and most of which couldn't put out more than 12W.
As the technology has advanced, we've created devices that are capable of firing low ohm atomizers
and are regulated. Essentially, people used to build their resistance according to dial in their preferred vape (because you're catering to the 4.2V of your 18650 battery in a mech mod). In a regulated mod, you're able to build virtually any resistance and create a similar vape to the one that is preferable to you, whether that means a lot of clouds on a low resistance atomizer or a lot of clouds on a high resistance atomizer. I remember when the "Duke" first came out, and the first time I used one I knew that this was the future. 2 batteries meaning a real full day of vaping, adjustable voltage (3-6V, max of 60W if I recall correctly).
An example is my .5 ohm build. At 5-6V or 60W it's a really nice warm vape, chucks plenty of clouds, has a short ramp-up time, and is my preferred vape. This same build is basically nonfunctioning on a mech mod. Too many wraps of a thick gauge means it takes forever to heat up, and when it does heat up (~4 seconds into a pull) the vapor is lackluster at best. Not only that, the added benefit of built-in safety features is also appealing (particularly to new vapers). With a mech mod there are lots of intricacies of battery safety, for example, knowing when your battery is fully discharged, knowing not to insert your batteries upside down, knowing the limitations of your battery's CDR. With a regulated mod your device won't turn on if your batteries are upside down. You'll get a "LOW ATOMIZER/SHORT" warning if your atomizer is too low of a resistance. You have a battery indicator to tell you when to charge your batteries. In essence, it takes a lot of the thinking/explanation out of the process of getting nice, thick, satisfying clouds (which is the primary thing a lot of people look for when going to vapes).
In the end, it's personal preference, but all my mech mods have been shelved as of about a year ago in exchange for high wattage regulated devices. I just like the form factor of a box mod, and it's nice not having to carry around multiple batteries all day. The added safety features have probably prevented some mishaps too, as my drunk self isn't always keen on charging his batteries at a reasonable level. Also, for a new vapor who wants to jump straight into vaping, I will 100% recommend a regulated mod over a mechanical mod simply because they're
far less likely to hurt themselves and they have a wider range of what they can throw on top of it (maybe they realize their favorite resistance/wire gauge is one that isn't suited for 4.2V).
..And that's not even getting into the topic of temp controlled mods, which seem like the "next best thing", which implicitly require a regulated device.