Depends on your personal needs. We started full timing in a '91 Beaver Contessa (37') with no slides and a 250hp Cat. Before we retired it served us well as a weekender and occasional vacation accommodation. But a funny thing happened to it when we started living in it full time: it started getting narrower and narrower and didn't want to go up the hills when we came out west. Going down long steep grades was just too much of a thrill for me.
Two years in, we bought the present coach: 2006 Beaver Patriot Thunder, 4 slides, 525 hp Cat, Jake brake. Oh yeah, washer and dryer on board (no sitting in laundromats for 1/2 a day once a week). The workmanship was not as nice as the '91 Beaver but it suites our needs quite nicely and we could afford it. YMMV
In any case, that was just an example of how your needs may change. If you buy a new MH now, how do you know it will fulfill your needs when you go full timing and your needs change.
In the mean time, jump into your MH and head down the road. "Boldly go where no man has gone before. Live long and prosper"