Yes, handwritten addresses are good ettiquette, but as you said, it is the 21st century. If you are going for an all-out traditional wedding, than handwriting is probably the way to go. That said, I doubt anybody will be offended by a printed address label (unless you have one of *those* relatives LOL).
With printed labels, you could always pick a fancier font and maybe even change the color of the text to make it more personalized.
Another option: perhaps you could find a way to print directly to the envelopes? That might look a bit more formal than sticking labels on? Again, I don't think it REALLY matters, but it was a thought that popped in my head.
Personally, I hand-addressed everything for my wedding (sans save-the-dates, as we didn't mail any), but that is because I like my handwriting and I had a verrrrry small wedding. If I were mailing out invites/thank yous/etc. for hundreds and hundreds of people... I totally would have printed labels.
In the end, though, I think it should be what makes you happiest. If hand-addressing is simply going to STRESS YOU OUT... then don't do it.
... I'm afraid I'm not much help on the poll, though. LOL! I don't know which is "better", just that I think either are acceptable in this day and age.