Normal non-tank atomizer and drip tip on a sealed manual battery.
And I recommend unflavoring non-nicotine juice to vape between the flavors if you really want to clear out the old taste.
First I line up the juices from most delicate to most strong to most clingy. I start testing at the delicate end.
I drip one flavor, try it, blow out the atomizer, prime with the next liquid and vape that until I get a sense of how that is alone. I separate out the ones I think I like then give them longer tests. Sometimes I even put one in a foam-stuffed Joye 306 cartridge for extended testing without dirtying a carto.
Ways to transition from flavor to flavor more cleanly:
Instead you can blow out the atty then vape unflavored between until you taste and smell nothing then blow out the atty and try the next flavor.
And instead of that you can rinse the atomizer, shake and blow out, run it slightly to boil off water, drip the next flavor.
Warning - it's easy to get over-nicced when testing juices so pace yourself.