RetireJapan

My real estate agent mentioned that a couple of the houses that we looked at were built by good developers, one was Sumitomo, and I'll have to try and remember for which house the other one was. It was implied that there were bad developers, but I can't imagine him actually telling me "oh this is not a good developer" after I say "I'll take it!"

Is there an available list or ratings website to see and compare developers? I'd rather eliminate these before seeing them in person.

Cheers

They will say that about any big developer. And as you suspect, they will never say that some developer is bad.
There are plenty of rankings of developers on the web, but my impression was that they are mostly about their pre- and after-service, not about the quality of the building itself.
Every developer is different in what they specialize in - design, all wood interior, insulation etc. - but I would say, usually you get what you've paid for.
Tateuri, from any developer, are usually cheaply built. And 90% of the houses on the secondary market are tateuri.
If you are buying a new tateuri, you can estimate the price of the building by deducting approx. price of the land, and if you get anything below 1500 man, then it's one of those infamous Japanese houses with lifetime of 20 yrs. If it's 1500-2500, then it depends, if more than 2500 - then it's probably more or less decent house.
All of the above are just personal impressions of some one who was trying to buy and then build a house, so take it with a grain of salt.

Oh, and those ranking are only for big developers.
There are no rankings for small developers/komuten.