My preference for each:
Star Wars: SSE 1.6. It’s 1080p and 100% the theatrical version.
Empire: Grindhouse, for the same reason as Star Wars. However, its colors aren’t very good and it’s not GOUT synced, and it’s super beat up.
Jedi: Grindhouse, for the same reason as the other two. Despecialized 2.5 is a great choice too.
TPM: I mostly watch the DVD version, but there’s also the Laserdisc.
AOTC: DVD
ROTS: DVD