Empire is clearly the best for being the middle third of the story arc and setting up the real drama of the final installment, without the tedious scene-setting and slow build up of New Hope or the sheer idiocy of a Galactic Empire being defeated by teddy bears with rocks in the concluding chapter (plus all the cloying sentimentality at the end - but LOTR is the main perpetrator of this crime).
The three originals will always be better than the new trilogy, chiefly because they weren't such a surefire bet at the time, so there were actual editors and script-writers involved. By the 90s, George Lucas had enough money to do what he liked and proceeded to come up with a pile of monkey spunk. I've seen excerpts from the first drafts of the originals, authored entirely by Lucas, and it explains a lot with regards to how he messed up the new films - he can't write. He can do plots, but the actual detail of a story escapes him.
The new trilogy goes in reverse order for me, Sith (which I'm actually quite fond of) followed by Clones (good battles) and Menace trailing in a pitiful third, a choking pod-racer pushed by a cast of actors lumbering along without direction or motivation, eyes downcast as they realise they are the unnecessary link in the chain, and that the new trilogy should have started one film later and led us right up to the moment that New Hope began. Although, I do love the final shot of Sith and the full-circle it takes us.
As for memorabilia, nothing can beat making your own gaffa tape light-sabres to break over each other's backs down the dunes...
