I'm using a dual 18650 DNA30 with a clone Stillare dripper. Vaping at 30W and 70VG is a blessing to my lungs.
I'll recommend something a long the lines of DNA30. Don't settle for lower end APV that boasts VV/VW. Get the top of the line electronics like DNA20/30 chips. They don't come cheap for APV, but well worth the couple of hundred you might spend on them.
With a nice mod, you need an equally good atty. I like drippers because I'm cloud crazy, and also because of the convenience of changing my juice as and when I like to. But do that note, drippers are not your regular CE4 tanks and they require skills to work with and actually make them perform. Same goes with all RDA like kayfun, genesis tanks and drippers alike. Knowing what to get and how to use them will bring you a long way.
But likewise, with proper equipment, you need safety as well. Don't settle for tom-....-harry brand batteries. I use only Sony VTC5, EFEST 30A 18650 and AW IC protected 18500. Read up on battery safety. I'll recommend AW IC protected over IMR for the barest of minimum. Why? Do a little bit of research. IC protected batts prevents shorts (supposedly not supposed to fire if short is likely to occur) and IMR only reduces the explosive tendency. Make your choice.
Now you know what to get, fix your juices first. It's the cheapest way and most straightforward way to getting your Vape game right.
Get good juice with safe contents, and of course of a flavor that you can consistently find satisfaction. Juice is not all about flavors. Find a balance for throat hit, vapor and flavor. Throat hit is from nic, vapor is due to the VG/PG content and flavor is basically your preference. Unless you find a juice you can use as a control for your set ups, you can't find the best set up at all. You'll only find that juice VTF is inconsistent. Do take note that cream based juices perform very differently compared to none cream based juices. Especially so for drippers. Tanks will enhance the tastes and make full use of the creaminess in cream juices like vanilla and custard.
Vape wisely and Vape safe.