Most of the tanks I currently have in rotation are top fill. As a result my tanks rarely get separated from the mod they are mounted on.
Granted, some top/side fill solutions work better than others. I invested in multiple 'Top Tank Minis' only to find that the V0 RTA (with the tiny slits for
juice channels) has any hope of not leaking after a refill. The V1 and V2 Kanger RBA leak gobs. There is still always the option to bottom fill these tanks.
I've never had the Kayfun's and their clones leak after filling. I think the JFC on these are likely the most effective in the industry.
I've had the best luck with the OBS Cirus and Lemo2 side fill's. Both can benefit from inverting the tank right after filling to reset the pressure in the tank.
I have a set of TFV4's with the single RBA that sometimes leak sometimes not. With no JFC these tanks have to be inverted and let the extra juice run out the drip tip.
Personally I think the JFC on the Griffin's don't have tight enough tolerance to be effective. The juice will run out the air holes with the JFC closed on mine. (fill quick, cap, invert, open JFC, set right side up seems to help)