I haven’t seen a single full Star Wars movie.
If you ever decide to watch just one to say you did it, the two most worth watching are A New Hope (1977, originally titled Star Wars) and it's direct sequel The Empire Strikes Back (1980), which is considered the very best one by most.
That's the conventional wisdom, but it's wrong.
A New Hope is only so well regarded because it's the first one, otherwise it would be considered okay at best. ESB is very good but it's overrated because the most iconic moments came from it and original Star Wars fans latched onto it due to nostalgia. That also explains why the prequels (which have two okay films and one excellent one) are criminally underrated, because the people who saw the originals as children/teens then saw the prequels as young adults and obviously they didn't meet their idealized standards.
If you want to watch the Star Wars films, you should watch all six (the Disney garbage doesn't count) or none at all. There are several possible orders, and they each have their pros and cons, but order of release (4-5-6-1-2-3) seems like a safe bet.