I've heard about different types of mkiv supra but to be honest, Idk which is best, what makes it the best and what makes them all different. Although, I get its something to do with the JAP specific supras
Does Google or DuckDuckGo just not work for half the planet anymore?
SZ - Non turbo 2JZ-GE nonvvti, available with an auto or weak ass W58 5spd manual.
SZ-R performance package 2JZ-GE non turbo nonvvti, available with the Getrag V161 6-spd after ~96 and almost always has a factory Torsen LSD.
RZ - Twin turbo, available with an auto or the Getrag 6spd trans. Early RZ 6MT's got the bigger version of the rear diff, went to the small diff in '96 or so. VVTi 2JZ-GTE engines came about shortly thereafter.
RZ-S Twin turbo, 'sport' model introduced in '95ish with limited luxury features intended to lower the entry cost of an RZ. Typically came stock with the small brakes, 16in smaller wheels, etc.
GZ - Twin turbo luxury model, always an auto trans, typically had leather and all the nice interior stuff. Discontinued around 96ish.
Whichever one is 'best' is subjective to your desires and performance goals.
Here's another great source for all the nitty gritty on all the JDM models: