there is no "best" there are positives and negatives with all of them.
you have to find the features that work for you and what your looking for in a
device and the way it vapes. one may have a great top, but a not so hot button, one may have great conductivity but only available in 18350 size.
almost all of the higher end models work well, but may not be the
device you prefer.
the best thing to do is just start digging in the APV forum, almost all of the better ones (and even the clones) have extensive threads discussing just about everything about a certain model. then choose one that appeals to you personally.