Ask 100 fans the above question, and, after factoring out personal allegiances which sway people's responses, you'll always get the answer Kashima Antlers.
Even newcomers to Japanese football will know how they last year defended their 2007 league title; a crown claimed along with the 07 Emperor's Cup. That alone paints a fairly clear picture of the modern J. League, but how about over the full course of the league's history?
Using a totally arbitrary system conceived by yours truly while down the gym, lets find out! Going back as far as the professionalisation of the game in 1992, teams are awarded:
League title - 3 Points
League runner's up - 1 Point
Cup win - 2 Points
Cup runner's up - .5 Points
Cup points count for both domestic and continental competitions. Show-piece games like super cups and so on aren't counted. So using that system, here we go:
Kashima Antlers 32.5
Jubilo Iwata 21
Yokohama F. Marinos 18
Tokyo Verdy 18
Urawa Red Diamonds 15
Gamba Osaka 10
Yokohama Flugels 6.5
Nagoya Grampus 5.5
JEF United 4.5
Shonan Bellmare 4
Beyond that you start getting into the realms of (so far) one-off cup winners (Oita) or several time cup runners up (Cerezo).
No surprises at the top of the table, then. Kashima are head and shoulders above all comers. Jubilo are up next, and while their time came and went a few years ago, it reflects well the various J. League records they set and which still stand. Marinos always threaten to reclaim, at least in part, their glory days, but it's probably safe to say that Verdy are well past their best. S-Pulse come in far-too-far-below-Jubilo at 6th, joint with Asian Champions Gamba.
So anyway, what made me want to spell out the above? Most people don't need proof for what's self evident. Some people however, a good example being Shintaro Kano of The Daily Yomiuri, seem to be living on another planet.
In an article bemoaning the lack of fight of many Japanese fans, Kano signs off with this absolute gem:
"Is it a coincidence that the fans of Urawa Reds, the most successful club in the J.League, are the toughest to please?"
Is this a well disguised tongue-in-cheek dig at the perpetual Urawa hype-machine, or does he actually believe it? We've already seen it isn't the case, but worse that that, it's not anywhere close to reality. Even if you dispense with my convoluted points system and look at titles won, Kashima come in first with 12, Verdy and Marinos next with 7, followed by Jubilo with 6. Only then do you get to Urawa, sitting level with Gamba at 5.
Average league placings put Kashima first (3.3), Jubilo next (4.5), then Marinos (4.9). S-Pulse pull in a respectable 6.8, and it's only after this that you get to Reds. Last year's finish of 7th should be no big surprise; it's perfectly in keeping with their J1 average - also 7th.
I think what Kano meant to write was:
"...fans of Urawa Reds, the most successful club in the J.League in 2005 and 2006 (but don't look either side of these years as other teams were winning more), are the hardest to please?"
The problem is, that doesn't back up his underlying point of unforgiving fans = successful team, so he seemingly plucked something out of thin air to lend credence to the theory.
Urawa are a big, strong team. They have more money than anyone else, and they've had the potential to deliver for years. This is all common knowledge, but save for a brief burst a few seasons ago, they've consistently failed to produce. Given everything, you'd have to be pretty blind to keep peddling the myth of "most successful team".
Shintaro Kano is guilty of lazy, not to mention entirely inaccurate, "journalism". Re-writing history to suit your own ends? That's how dictators get started, you know.