Mine is too many to list. But here goes my try at it
1. Flavour profile
Most local juices are mainly one dimensional. Fruit, sweetner, mint, colouring. Bam! Slap some "premium" label and it's ready to go. Of course this is highly subjective but I find it too bland to my liking.
2. Yes. The nic.
3. Food colouring in ejuice.
Self explanatory. Health concerns.
3. Ingredients used
US made and etc. Some brewer I personally know get their ing from oversea but there's a rumour floating around that brands like Star Brand flavouring is also used locally. Now that ruffles my panties.

I could ramble on but am using mobile right now so  ¯\_(ツ)_/¯
But you get the idea. Some are just not worth the price they slapped onto
Yes. Unless you're using Ti wire, even 0.2 ohm is too high.
Not hot meh? I usually vape at 450f and this lil thing made me felt like giving Satan a blowjob. Did a dual clapton .3 ohm and sold it the next day.

Depends on your mod actually and if could support Ti mod or not. My D2 could go up to .3 ohm in Ti mod so TC could still be done within that limit.

Past that and I'll burn my cotton or worse, titanium dioxide, since it'll just read it as a normal kanthal. Know your mod people.

I won't call it my 'best' yet since I still don't have Ti wires but I did get some from a friend of mine.

Did a simple spaced dual coil 26g 8 wraps on 2.5mm coming out around 0.16ish. Just wanted to taste the hype. Contact coil gave me a weird taste, I may or may have not inhaled a Class 2B human carcinogen with that but spaced coil gave me a clean vape on par with 316L SS.