I was really torn...
...but I went with Star Wars, and here's why:
The Godfather had that really crappy final act with Sofia Coppola--who turned out to actually be a very talented director (and not a bad looking dame at that
).
Die Hard was great for what it was, but there was really no flow to the story, they were more like installments rather than chapters--even though I love the last one.
Indiana Jones is without a doubt my favorite Action / Adventure trilogy, but the stories aren't tied together by one bigger storyline like Star Wars or LOTR. It kind of falls into that Die Hard category, where each installment is its own seperate entity, and not part of a bigger picture / storyline.
The No Name trilogy...definitely the best Western trilogy, but as far as consistency, well I'm more of a "The Good, the Bad, and the Ugly" fan, although "Fistful" is really good in its own right.
Evil Dead...who doesn't love Evil Dead? Bruce Campbell is awesome, but as far as it being the best? The best implies real character development, mythic themes, epic battles...
...Which is why I almost went with LOTR, but being that I'm old school and grew up with Star Wars, I had to go with sentimental favorite.