It's debatable.  Hence this post.

Tiger had won every major championship at least 3 times, with 4 Masters titles, 3 US Opens, 4 PGAs and 3 British wins.  He's won tight ones, laughers and everything in between.

If we are to take a quick look at Tiger's biggest wins - including the 2008 US Open - we'd have to look at these:

1997 Masters.  Tiger's first, and he won by 12 strokes, destroying the field and some 20 Augusta National records with his -18 winning score.

2000 US Open at Pebble Beach.  A record -12 US Open score, and won by 15 strokes.  His next closest competitor was 3 over par.

2000 Open Championship at St. Andrews Old Course.  His 19 under par was the best score in a major by anyone.  Ever.  He won by 8 strokes.

2001 Masters.  By winning, it meant that for 2 months Tiger held the titles to all four majors - the Tiger Slam was invented to categorize the event.

In my opinion, they rank as follows:

5.  2001 Masters.  Sure, it was historical, as the media had to create the "Tiger" Slam category.  But as a Major went, it wasn't all that memorable.  He carried a 1 shot lead after 54 holes, and beat David Duval by 2.  His -16 score was great, but not the best he'd carded at Augusta.  It was 6th title in total.

4.  2000 Open Championship at St. Andrews.  Setting the all-time Major scoring mark was just one of the memorable items from this win.  It was his second Open Championship.  What he did on those 4 days was simply obliterate St. Andrews.  His length and accuracy took away all of the hazards on the course, and the greens could not stop him.  Historically, the Open Championship does not try to set up the course as nastilty as the USGA, but they are supposed to be tough tests all the same.  Tiger made the Old Course simply look outdated - not something the members of St. Andrews want to consider.  It was stunning in its dominance.

3.  2008 US Open.  For as great as it was, and for all the drama, it was not Tiger's best win.  He had to fight the course more than dominate it, and were it not for a couple of tremendous shots, he wouldn't have won.  Making this one memorable was the Wounded Knee, and the playoff against a game Rocco Mediate.  Woods has prevailed at the Open in all kinds of ways, and this was simply another notch in the belt.

2.  2000 US Open.  The Open scoring record.  Winning by an insane 15 strokes.  Tiger played that 4-day tournament like it was the spring event at Pebble Beach, and not the Open.  He was perfect - as perfect as a golfer could be.  His striking was perfect, his putting perfect - Tiger showed in that event what he can do to even the toughest courses when everything he has is working perfectly. 

1.  1997 Masters.  He announced his greatness in this tournament by not only setting the Master's scoring title, he won by an amazing 12 strokes.  This was the "old" Tiger - the true grip it and rip it Tiger, the one who never saw a power shot he didn't like.  Yet it had traces of what was to come - the amazing scrambling ability, the touch on the greens, the imagination.  All of these things bundled into one man.  Tiger's stay on the "best player to never win a major" was extremely short-lived.  His dominance at Augusta that week led the course to "Tiger-proof" the course - something that many, many other courses have had to do since Tiger began playing professional golf. 

This isn't to say that his other wins weren't memorable.  His first PGA, beating Sergio would not have been possible without that critical putt late on Sunday to ice the win.  Later in his career, his playoff against Bob May again in the PGA was a highlight film - the shot of him excitedly walking after his putt, "shooting" it into the hole is a well-known one.  His pure domination at the Open where he hit driver only once, hit 92% of the fairways and utterly dominated the win after his father's death is another.  Yes, Tiger's 14 Major titles are all impressive, and all memorable.  But this one - the knee, the playoff, the challenge from Mediate - make it among his best...but not the best.

But just to make one final point perfectly clear.  We're not discussing the ranking of best major wins for any other player on Tour today.  Not one.  The only people that we can compare Tiger to are the titans of the sport - the Hogans, Palmers and Nicklaus's of the game.  No one has managed to earn the title of Tiger's Rival.  And until someone can start beating him more than once...