>>719768452
First question is do you have a decent rig that can run UE5 games without major issues? If so you're mostly choosing on a mix of aesthetic front, controls and content.
>Delta: has New Style for MGSV style controls with no sprinting, but comes at the cost of bullet drop for tranquilizer rounds and some odd changes to animations, while Legacy Style is just MGS3 with the new graphics. comes with Snake vs. Monkey, a new take on the Guy Savage secret minigame, boss rush, additional secret targets in every map to shoot plus a QoL tracker on whether you got them or not, and (most of) the Secret Theater with new additions, it's effectively definitive on overall MGS3 content
>Master/HD Collection: it's 60 FPS, 720p MGS3 with some graphical/cinematic effects fucked up, but mostly playable besides the changes needed for controllers without pressure sensitivity, Master Collection has a lot of bugs though; all that extra content mentioned above is completely missing so you're just playing HD Subsistence with some visual/audio issues depending on the version
>PCSX2 Subsistence: all the content that was supposed to be there, fan patches in the emulator itself for widescreen and 60 FPS if your computer can handle it (though if you can run Delta to begin with then this should be mostly fine), but the game was made for pressure sensitive buttons of the dualshock 2 in mind, requiring either awkward clunky usage of the controls or having some pressure modifier buttons to "simulate" different levels of button pressure as you play
Delta isn't inherently bad, but if you're autistic about MGS3 the New Style does a lot of little changes that have pissed some diehards off even if it's basically so much of a remaster that most quirks otherwise remain. But some people will just prefer the PS2 aesthetic. The only "wrong" way to play is Master Collection with no mods/patches to try to unfuck it.