Thanks to everyone who's posted thus far. There's certainly a lot of collective experience here and these have been fun to read.
A few quick notes on the productions I've seen (or that I can remember that I've seen).
American Ballet Theatre -- 3
David Blair (the production I saw the most; solid, old-fashioned. I was quite fond of it. Makarova-Nagy; Kirkland-Baryshnikov; Fracci-Nagy and Nureyev; Makarova-Dowell, Tcherkassy-Bujones, Gregory (not one of Nature's Giselles, IMO), Cynthia Harvey)
Baryshnikov's and the current Uncredited Production.
National Ballet of Canada - 2? I'm sure I saw Bruhn's (with Fracci and Nureyev, and Lotsofotherpeople and Nureyev; Nureyev got three entrances in that production

) Somewhere along the line I also saw Peter Schaufuss Ultra Realistic (blood dripping, mad mad mad scene) Giselle, but I can't remember whether it was with NBC or the then-London Festival Ballet.
Mary Skeaping's for Festival Ballet. I agree with Alymer; it could have been a great production

There were lots of things about it that I liked, but, as we've been talking about on the Hodgson and Archer thread, she started backwards, not really with the sources, so bits of Act II suddenly ended up in the reconstructed solos, and some corps work, in Act I, and it made you think that those dances were foreshadowings of what was to come.
National Ballet of Cuba -- the Wilis are a centipede. I've never seen such precision. I saw Alonso in this when she was 60, and she brought out the mime in the second act -- movements I'd always thought were ports de bra that suddenly became gestures -- and it was quite a revelation. I'm looking forward to seeing it again next season.
Bolshoi -- Grigorovich (Semyenaka and Possukhov, Semizorova and somebody, Ananiashvili and A. Fadeyechev; others on tape)
Kirov -- Vinogradova. An accidental (last minute substitution) performance of Makhlina and Zelensky that I loved. He takes the Standing High Jump Competition medal, in my book, in a nose-to-nose finish with a young Patrick Dupont
Berlin Ballet -- whose production? Nureyev and....Evdokimova?
Australian Ballet, Maina Gielgud. Pretty much the David Blair production, but she added something I'd never seen that I liked very much. It's a "borrowing" from a lost ballet, "The Ballet of the Nuns," at the beginning of Act II. She had the wilis, shrouded and veiled, come forward out of the mist. Great coup de theatre.
Royal Danish Ballet -- Kronstam's, of which I've written before. For me, the production that came closest to perfect, despite the fact that he turned the second act into a dream and double-cast Myrtha and Bathilde. But he had good reasons for it and, more importantly, it was done so subtly it didn't intrude. You could ignore it, or you could read all sorts of things into it. He had a few other things that I thought were very beautiful and I've never seen elsewhere -- Myrtha's branch doesn't break, but its petals fall off, slowly. The phrasing of the second act, especially in the dances of Myrtha with the Wilis, was very subtle and beautiful. All of the Albrechts (Hubbe, Lloyd Riggins, Peter Bo Bendixen) were very young and not yet quite ready, but the Giselles -- Lis Jeppesen, Heidi Ryom and an also very young Rose Gad -- were fine. Jeppesen was somewhere between Fonteyn and Fracci -- classical in line, like Fonteyn, but soft and nunlike, like Fracci. Ryom was very dramatic. Rose Gad had the most beautiful soubresauts I've ever seen. Everybody else looks like a kangaroo to me now. And her mad scene -- which, at Kronstam's direction, she did as trying to recover her balance after receiving such a blow, not going mad -- was extraordinary.
San Francisco Ballet -- Tomasson's. The best of his productions of "the classics," IMO, but still not ideal. Too many contemporary, i.e., out-of-period, trick steps.
Two local productions for small, semi-professional companies, one staged by Paula Tennyson (a former Ballet Russe dancer), the other by Paul Meijia. I loved both of them. The Tennyson one was really for high school kids, and probably nobody in the cast went on to have a career, but it was like a first-rate high school production of "Romeo and Juliet." There were no "cheats" in it, and the audience -- all parents and kids -- got to see a real "Giselle." The Meija one (for him and his wife, Linda Kintz, and a wonderful Myrtha named Christine Matthews) was very romantic, passionate.
Lots on tape, but they don't count. I still haven't seen any British production, and I would have loved to have seen the one Ashton did with Karsavina looking over his shoulder (and his peasant pas de deux -- for Sibley and ? -- and I want to see Paris Opera, too.