Gotta go with 77-91, if for no other reason, that's when i started to get into Lynch.  I saw Blue Velvet in the theatre, and it forever changed my life.  Around that time, I also had a "bootleg" copy of Eraserhead, which was considered something of a holy grail between me and my friends.  Unfortunatly, out of all those friends, I was the only one who became a true Lynch fan!  I watched Twin peaks in it's original TV airing, and it was truly the only television show that me and my friends in my dorm watched religiously. 

LH and MD are definitly my 2 fave things that came out after 91(except of course for FWWM). 

Ben:  "We've laid in a gala reception for your fair-haired boys tonight.  All of Twin Peaks' best and brightest."

Jerry: "We're holding it in a phone booth?"

It is a hard choice, but I feel like '77-'91 contains the "essential" works that people should begin with when viewing Lynch. Pretty much everyone who loves Lynch loves him because of one of these films, whether it's Eraserhead (which for the record, I don't really care for), Elephant Man, Blue Velvet, Wild At Heart, or Twin Peaks. On the other hand '92-'06 contains his last three films (hopefully not, but potentially his last films ever), which are definitely high up there in my ranking of his films. I consider Mulholland Dr. and INLAND EMPIRE to be his 2nd and 3rd masterpieces after Blue Velvet, and they are the only Lynch films that I can say are unqualifiedly great from beginning to end. However, they are in many ways commentaries on the themes of his earlier films, and probably cannot be fully understood without the benefit of his earlier works. The Straight Story is an incredibly moving film as well as proof that Lynch is capable of making powerful and endearing films that are accessible to anyone. So it's a tough call.... I think I'd have to go with the early films though, due to the sheer amount of work, and because of my memories of discovering these films for the first time, and realizing just how frightening, personal, and magical cinema can be.

That god damn trailer's more popular than Uncle's Day in a whorehouse!

I have to follow the crowd here, if for no other reason than 77-91 contains Twin Peaks. If it hadn't been for TP, I never would have discovered Lynch and it's still my favorite thing he's ever done.

I do have to say, however, that I deeply love Lost Highway and Mulholland Drive. And FWWM is my single favorite Lynch work. So it was a tough call.

"What? Did your life pass before your eyes? Cuppa tea, cuppa tea, almost got shagged, cuppa tea..."

"watch out for my cousin.."

"Harry, I'm going to let you in on a little secret. Every day, once a day, give yourself a present. Don't plan it, don't wait for it, just let it happen. Could be a new shirt at the men's store, a catnap in your office chair, or two cups of good, hot, black coffee. Like this."  -Dale Cooper