Top fill.
The podstick slider that covers the ptf is a nice dust blocker but… if using a 100ml bottle it gets in the way. Thankfully the podstick arrives with a nice little spare bottle.
Zero bottom fill is good if you keep a napkin handy to soak up what remains in the concave lid. Otherwise that affects contact of the
tank to the battery.
The Play was my favorite ptf. Looks like the degree is similar.