I have various tanks (MAP, Cartzilla, CE2s), and various SC and DC poly-filled cartos, regular capacity, XL, and strangely huge. I personally favor Boge LR (2.0 - 2.4 ohm) poly-filled cartos for my fat bats and 18650 mod. Sometimes I'll use a tank, but most often its the Boge LRs. They just do it for me in terms of hit, vapor quality and flavor. I use a drip tip on them, easy to top off, and use them for a couple days or so before tossing them in a mug for future cleaning. I get 4 or 5 cycles out of most of them.
Lately I have been enjoying the 510-t bats. 3.7V autos. My VG juices don't wick well in the 510-t carts, but a 3.0 ohm poly-filled or CE2 clearo on them are very nice. A soft rubber drip tip allows comfy puffing while the hands are busy with other things. I find those combos to be very satisfying.
Of the tanks I've tried, the Cartzilla (ecigexpress) is the best I have tried, but then I've not tried any of the tanks that hold a carto inside. Downside of big tanks for me is I rarely want to just vape one flavor for hours and hours. I prefer smaller cartos and drip into them whatever I want. But I also want more time with it than an atty will give.
As with everything here, YMMV, and personal favorites of one person can be dreadful for someone else.