This is what we got... http://www.jayco.com/products/class-c-motorhomes/2017-redhawk/26xd/
We had the 23XD, but just a bit too small, and no couch... so last year ye traded up to the 26XD. It's only 24 inches longer, but has the separate bathroom, walk-around bed, and dinette. It's also the only one we found that has a 2 year warranty, and seat belts for all 8 seating positions.
Yes, it's a one piece front cap, and the seams are on the bottom, very little chance of a leak.
If you can, take the factory tour, it's free, and really gives you a sense of the quality of the build.
We considered the Mercedes platform, but after talking to other owners, we decided against it. Folks that we talked to said that it was under powered, and expensive to have power train / chassis work done, and difficult to find mechanics on the road.
We went with the Ford E450 chassis, as it's ease to work on and get parts for, has plenty of power and load capacity, and now has the 6 speed transmission (quieter, smoother, and better mileage).
What sealed the deal for us was the factory tour, and the 2 year warranty. NOTE, you can get a REALLY good deal on the 2016 models, now that the 2017's are out!
Good luck and happy & safe camping.