It's a journey, so it is.
There is no general "flavour-chasing" setup. Some people are going nuts about dual coil for flavour but as for me, I prefer a simple single vertical single coil with as little airflow as necessary (but just enough so I still drag in enough liquid through the wick into the coil) and I'm still trying to find out whether I like 3mm ID more than 2.4mm. I don't have a coil master, only a set of clockwork screwdrivers but in general, this is what I found out:
The smaller the gauge, the thicker the wire (That's why 26 gauge Kanthal is thicker than 30 gauge)
The thicker the wire, the longer it needs to heat up at low Watts
Also, the thicker the wire, the less resistance you have (Because there's more "room" for the current to go through)
The longer it needs to heat up, the cooler the vape.
I'm pretty fine with 28 gauge Kanthal with 2.4mm ID - Depending on the number of wraps (Usually between 6 and 8) I end up with something between 1.0 and 1.5 ohms. It's not a too warm vape and with as little airflow as necessary I get pretty decent flavour.
Then again, I'm using an S.O.D. clone (Which is
this little fella here) and it's TINY with a short, stubby drip tip, so the vapour doesn't have to travel as long.
As for RTAs... well, I'm happy with the GEM RTA clone. The smaller the deck, the less room the vapour has to "swirl" around and condensate.
As I said, it's a journey and noone can possibly tell you "This is the land of milk and honey" - I mean... I got better flavour out of a bog-standard old EVOD where I popped my own coil into a stock head, wicked it with cotton and used it at 4.2 Volts than I got from a goblin mini clone (Which I'm trying to give away now) with a 1.0 ohm coil at 15 Watts. Other people would call me nuts about this but it works for me!
Personal preference, that's all it is about.