Goblin mini is better IMO, it's smaller, same
juice capacity (unless you use the extra capacity tank on the goblin, which mutes flavor), slightly better flavor, subjectively looks better, mine was machined better than my OG goblin. The gmini wicks better, the fill port screw is better. The airflow is much smoother / less turbulent on the Gmini vs the OG Goblin. People also complained about leaking more with the Goblin than the Gmini it seems like.
The OG Goblin has a few things on the Gmini too though, it can be top filled easier than the gmini (although the Goblin is not intended for topfill, it can be done). It takes a 510 drip tip without an adapter. Those are about the only things it has going for it over the Gmini.