vaperesso transformer RDA(22mm) is nice and small fitting most single battery mods, can be a single coil to a quad coil build, postless or velocity styled posts, can be a bottom feeder(has the hollow pin) if you get into squonking at some point, and it has two caps with interchangeable tops for clouds and flavour with top airflow(no leaking).
coilart azeroth RDTA(24.5mm) is a genny styled tank/RDA combo that is easy to build on, with a goon styled deck, a nice tank underneath, gold plated and side filling with several different chuff caps with top airflow(again no leaking).
kangertech pro tank 4(22mm) solid tank with a dual coil RBA, 5 ml, and top side fill, doesn't leak, plus factory coils can be bought when feeling lazy, and airflow in both base and driptip.
i have all 3 an absolutely love them