Best Class C Motorhomes

The answer to this question is going to very largely depend on what your budget is. If you can provide that then we can probably provide some feedback.

I think Nexus has better quality than others.
http://www.nexusrv.com/http://www.nexusrv.com/

Also:
Coachhouse
Lazy Daze (no slides, but with the big windows)looks bigger from inside.

For fuel economy look at a Class B+ like the Mercedes diesel powered Roadtrek (22 MPG) and the E-450 based Phoenix motorhomes. The Phoenix with dual slideouts provide a great deal more interior space than the average MH of this size.

Don't ignore purchase price as a $10,000 savings will pay for a lot of fuel. Diesel is also expensive in the USA, usually selling for 10-15% more than regular grade gas. Any gain in MPG with diesel is offset by the higher cost per gallon at the pumps.

I'm one of those who watches the roof, and fiberglass is far better than the membrane types, as it means the seams can be located at places that the wind isn't forcing water into the vehicle.

Ron Dittmar has an excellent explanation for what to look and what not to get, and this can save you tens of thousands in water damage.

Were I looking for a class C right now, I'd see about a FR Solera, either a 24R (gives one a sorta-walkaround queen bed in the back, as well as 27 feet of length in a 24 foot package), or a 24S, which everything works well, even with the slide retracted.

Something on a Mercedes Sprinter will be right there at 24-25 feet and have good fuel economy. On most dealer-sold brands, you can expect to get something like 25% off the list price.

Itasca Navion/ Winnebago View
Forest River Solera
Fleetwood Tioga DSL, Jamboree DSL, Jamboree Ranger DSL, and some other Tioga something DSL
Four Winds Citation Sprinter
Phoenix Cruiser Sprinter

Some people worry about the type of roof, with fiberglas being more desirable than a membrane type.

Ron Dittmer posts a nice rundown on body construction that would help you from a quality standpoint. You more or less get what you pay for.