I'm certainly no expert, and this is just my personal experience and opinions based on what I was looking for out of Ecigs.
When I first started vaping 3 or 4 months ago, I started with the cheap disposables and Njoy kit you find a gas stations and was severely disappointed. The disposables tasted horrible and the Njoy electrocuted me when the battery fried about 3 puffs in. But I knew if I could find a perfected version of the concept, I could be happy and finally wean myself off analogs.
So, being that I am something of a tinkerer when it comes to "techy" stuff (I bought my last prebuilt computer in 1994 and have built my own ever since) I assumed the mods had to be better in every possible way to something so pedestrian as the minis and I started trying every mod I could get my hands on. I also bought huge amounts of sample packs of juices in every flavor, mix of PG/VG and nic strength I could get my hands on. I spent well over $1000 the first month, was still unhappy and was still smoking nearly a pack of cigs a day.
Most of the higher voltage mods only create an illusion of doing more as they burn juice hotter and faster. It's akin to emptying a cigarette into a wide bowled pipe and using a torch lighter to fire it up. The huge cloud of vapor was impressive. The fact that I was coughing it out because it was too overwhelming, not so much. I ended up taking really small hits off them and was just wasting their capabilities.
I finally came to the personal conclusion that, other than the superior battery life some of them offer, and their ability to handle poorly concocted juices which have ingredients with an excessively high flashpoint, mods are really only useful to those for whom vaping goes somewhat beyond simply replacing analogs. Since none of those was an issue for me as I tend to use juices that are formulated for and tested to work well with the capabilities of my hardware, I wasn't looking at vaping as a hobby and I didn't need the capacity that the mods could offer, I was over complicating it.
To that end I bought a Volt. It vapes well formulated juices very well and offers many battery/LED combos for a bit of style (I also considered the Bloog but it was continually out of stock). It's simple, comfortable, gives a satisfying experience with the juices I use* and isn't as likely to get me tackled by TSA at an airport as a big battery mod.
I got 5 different batteries which included USB and wall chargers, a PCC for an emergency charge, and a couple packs of blank carts. I also picked up a Car USB adapter at Walmart for $6 since I travel long distances by car occasionally.
I then bought samplers of the specific flavors of juice that I liked (rather than continually experimenting with flavors that 9 out of 10 times I didn't like at all and was just wasting money on) in various different ratios of PG/VG (where possible) to find which ones worked best with it for my flavor/vapor preferences. And I'm now completely happy and am down to only a couple cigs a day and will likely be able to quit entirely soon.
Mods are great if you approach vaping as a hobby, enjoy the tinkering aspect, have a huge lung capacity, like huge hits and/or enjoy impersonating a dragon.
But if you just want to replace analogs, the KISS methodology will save you a lot of needless frustration. A decent mini, some spare batteries, a travel charger and (the hardest part) a couple flavors of juice that are formulated to work well with your hardware are all that most people need.
*In case anyone cares, the juices I use are Cowboy from Smokeless Image, a light menthol from ULTRApure (I'm still looking for a better one) and the Organic Orange Cream from Vaporite for an occasional sweet treat. I smoked Marlboro Lights for 15 years. I don't need 20 different flavors to replace them.