My very personal rankings:
1. The Masters--As Matt W. points out, it IS the beginning of the season, and I live in GA. The beauty is awesome, and the limited commercial telecast from the cathedral is captivating. They also have the greatest theatre in championship golf on the back nine.
2. The British Open--I love the early morning telecast, the totally different look of the courses, the names I've never heard of, the wild swings in the conditions, and the quirk of the whole thing.
3. The U.S. Open--a close third, but getting more third. The USGA is good at many, many things, but I'm just not sure that they are very good at this particular tournament. They seem somehow to have tunnel vision about par, and every year it seems less likely that heroics will win. Sport is about heroics winning at least as much as it is about tragic collapses, but that is getting lost at our Open. Still, it is the U.S. Open...
4. The PGA--a few years ago seemed on the brink of extinction as a major championship, the PGA has revived. They seem to be taking a much more measured approach to course setup, and not feeling like every course should be set up the same, or that a low score is the end of the world. The PGA has had some very, very compelling finishes in recent years, and some of the shine is back on the event.