I'm with r055co, depends on the deck. The 3 I've tried so far are the ehpro bachelor, kayfun v4 (clone) and v5 (clone). All are 22mm atomizers but the easiest to me is the bachelor since it's postless. No posts and the design of it allows for a longer coil (one side to the other). The hex grub screws are easier to manage with the allen wrench.
The v4/v5 of the kayfuns share the same size diameter but the posts take up some room and the hold down screws on the v5 (I think that's the one) are larger than the v4. Either that or the other way around, one set of screws are tiny the others are microscopic. Makes it a bit of a pain in the ass by comparison to the postless.
Just my impression anyway, they're still far easier to build on than trying to mickey mouse rebuilding the coils in non serviceable stuff like clearo premade coils/wicks. A velocity deck might be easier, the trouble I run into with the decks on the kayfuns are keeping the coils straight while clamping down the leads with one lead facing one direction and the other lead 180 degrees opposite it makes the coil want to twist sideways until it's tightened up. A non issue when both leads are facing the same direction. They always take nice macro photos zoomed in and make the decks look nice and roomy, then you get it in your fat booger pickers and it's like seriously?