I'll add my 2 cents here. We have been RVing for 32 years and have owned 7 motorhomes. Started with a 19' Winnebago LeSharo in 1986 and eventually got up to a 39' diesel pusher when we were full timing. Then downsized to a 34' Class A and now have had a 28' Class C for over 12 years.
The reason that the RV industry makes so many different sizes and configurations is that it's "different strokes for different folks". That being said, it does make it very difficult for new RVers to decide what's "best" for them. In our case, our needs changed over the years (from weekend RVers to full time and back to short time travlers) and we bought different sizes and types of RV to match our needs at the time.
We have had out current 28' Class C motorhome for so long because we just can't find anything else that we like any better. Strangely enough, the RV industry seems to have forgotten the "mid size" Class C. From what we have seen in the past few years, the choices seem to be the smaller 24'/25' Sprinter models or the longer 30'/32' models built on the Ford E450 chassis.
We think that a 27/28" Class C is a good compromise. We wanted a walk around queen bed in the rear and looked for the shortest Class C that we could find that had that configuration. The difference in having a 3' to 4' shorter CLass C means a shorter wheelbase and much tighter turning radius - - we can make a 180 degree turn at a 4 way intersection on a country road - - something that the longer wheelbase Class Cs cannot do - - and we have done that several times!
We have lived in our 28' Class C for up to 6 months at a time and know that we could full time in it if necessary - - but some folks would certainly find a motorhome that small to be too small for full timing.
In any case, as others have suggested, by all means rent an RV before buying and when buying consider a used unit for your 1st RV. Once you've decided what size and configuration works best for you, you can move up to a new RV.