Based on numbers, shorter one has a 60% ratio of WB to length and the longer one is a little less favorable at 57%.
That ratio tries to identify good handling, which is in turn based on good weight distribution. So, even though 60% is very good (I think 54% is considered minimum), the real issue is the actual weight distribution. It'll change as you load it up for travel, so where is the Storage, how will you load it, where are Tanks and will they be full/empty, what will you carry on the back, etc. etc.
You want at least 1/3 of true, loaded weight on the front axle. Some say at least 75% of front axle rating. If it's a new E450, then 75% of 5000# or 3750# and that's minimum. So include a truck stop in your test drive and get the actual total and axle weights now. That's a starting point. Some mid-size C's, say 26-29-ft, have a short wheelbase and heavy rear overhang. That's because the stylist wants to offer walk-around-queen in smaller coaches. UNLESS the wheelbase is adequate, that results in poor handling from a light front end, and possibly an overloaded rear axle. By your numbers, I don't think that will happen in either of the coaches you're looking at. Unless you hang two motorcycles off the back...
