There are many things to consider here. First and foremost, it'a where youlive or where the home will be set. You don't want to purchase from a company in Pennsylvania when you live in Arkansas. So you should look into companies in your region.
Next, how large are you looking? Some manufacturers will only do small to moderate homes while others will only do large homes. Others will only do custom homes.

So there are questions to answer brfore anybody says: Use my manufacturer! Because if they're on one coast and you're on another, the transportation costs can kill you! A good rule of thumb is $1.50 per mile from the factory for each box needed to build the home. A simple ranch is two boxes. And if they have to go 1,000 miles....

Im in WA, looking for a modest home, no McMans. Basic 2.5bdr 1.5bth.
Many 'mod' sites end up being manufactured sites.
Thanks for your response....

I would be interested in hearing the answer for Missouri. Looking for a 3-4 bed, 2+ bath ranch style, probably 1900-2000 sq ft.

hors,

I don't have any specific names for you, but have heard that a number of people have purchased some good quality modular homes from up in B.C. (not sure if there are also some in Alberta)

I can help out those in the NE. We just finished a custom modular and love it!

In NY there is a company called Westchester Modular and they make a fabulous product. The best thing about them is that they have standard items that are upgrades to everyone else. Upgrades cost money and it adds up quickly. We didn't go with them because we could not afford them. We have a family member that is a Excel Homes/Avis America dealer so we went for the family discount.

Excel is the parent company to Avis America. They make the same product, but Excel is a better known name so you pay more for it than an Avis America home. The quality is terrific on our house.

Penn Lyon makes a modular. Ritz Craft make a modular. Superior makes a modular. Elite makes a modular. Pinnacle makes a modular. There are some fabulous modular companies out there and some not so fabulous companies. Check references on your dealer, check quality on the modular company and be sure to get everything in writing.

http://home-and-garden.webshots.com/album/550219766XcLVEL

IN Bennington, VT there's a community being built with Westchester Modulars. I dare anybody to drive by those houses and be able to tell right off the bat that these are in fact modular homes. They're quite nice, and expensive.