Humm..... premade coils
The two premades that I still use are for the Atlantis2 and Nautilus tanks. The Atlantis2 coils I'm using work great, (I'm on my 2nd coil) and I'm still on the fence on the Nautilus coils as my VV/VW setups for those tanks was working well enough without TC so outside of saving the coils/cotton from dry hits I'm not sure it is worth the added expense for NI coils in that application.
My "SubTank" (as in Kanger) journey started with ready made Ni coils with 0.15ohms marked on them. They seemed to work ok but I've since added STM tanks with homemade NI200 builds on the included RBA deck. (recently I added to full size subtank clones to the mix) Most of these have different flavors and are used much less than my main tank (which is unflavored)
Lastly is the Lemo2 (and now two 'Limo3' clones). I've had the best results with the Lemo2. Just about everything I've tried works well enough to take out with me, some better than others.
Observations -
I'm not quite sure that 0.15ohms is such a great target resistance for some of the devices on the market and question even further the desire of some users to build at slightly higher resistance then the lowest that their device will fire at. As an example, recently someone posted a resistance/power chart compiled for the iStick TC40W which leads me to believe that >=0.15ohms might be a better target for that device. (I'm currently using 0.19ohm builds in my Lemo tanks on my SXminiM)
I also tend to question the available coil surface area in the pre-made coils, it seems to me that they have some wire stuffed in there that is much larger than 28-32AWG (what I've been using for my coils). The STM's lack the room to get very many wraps of very large wire in them, I tend to like 30AWG or twisted 32AWG wire. Sure, wicking the mostly flexible wire without deforming the coil is a challenge, however you can fit more wraps of thin gauge wire in there as long as you don't have an overly low target resistance your shooting for.
I recall some coils I made which had a fairly large ID and I had stuffed way to much wick in there and even more to much 'priming'. It took an enormous amount of power and some time to get the coil and surface of the wick up to operating temperature. The larger ID = more wire = more surface area = more wick did not add up to a better vaping experience.
Lastly, I think we need to keep in mind to that not everyone has the same vaping goals or are looking for the same type of experience. Then again, IMHO vaping with TC is a different experience than with VV/VW and I'm not sure that a TC setup can duplicate the VV/VW experience or if it really should.