Bigger is not necessarily the question. Consider the quality of the coach, mechanical components, where you like to camp, and your space needs.
We chose a Monaco Safari Trek to get the living space of a 38' coach in a 29' package. We like the first-class quality and the large bathroom. We like to camp in USFS CGs and state parks, and sometimes we boondock. Our Trek works well for us and many other loyal Trekkies.
Of course the Trek is unique - we have no bedroom. Our bed is in the ceiling and comes down at night. Why tow a bedroom - it's wasted space most of the time.
Each person finds the coach that meets their needs. I would purchase quality before length. Find the coach that meets your needs.