Already so many choices, but to add to your dilemma consider the Oumier Wasp Nano RTA, currently putting it through it's paces for review but already loving it, ordered another.
VERY easy to build and wick, this is the fastest build time I've tried and forgiving on wicking which is perfect for newbies to RTA's, Single coil with flavour to rival dual coils.
About to try a higher Ohm build in it to see if I can get the same flavour for less power, if so it's definitely a winner for me.
Only RTA I've owned to rival it flavour wise is the older Steam Crave Aromamiser V2 but that's got more parts to strip compared to the Wasp.