Depends what you want...

First off, a travel trailer make a lot of sense because you decouple the propulsion from the living quarters. But, then you might need a big truck (depends on size of trailer - most mid-size SUVs and compact trucks can only tow ~5000lbs). Another plus is you can drop the trailer at camp and drive to town/trail heads/etc. Downsides are total length, two registrations and insurance plans, etc.

If you don't need to live in it long-term, one of the fiberglass shell travel trailers (Oliver, Escape, maybe Scamp and Casita, though they're lower spec). The less plumbing, the better. The simpler the better. Less to go wrong/leak. They generally max out around 20 feet or so - plenty for a week here and there, but less than ideal for full-time living.

If I wanted full-time, I'd probably skip the Class B ("ship in a bottle van-based RV") and Class C (van/truck chassis and cab with box bolted on the back) RVs and jump straight to a Class A (bus or commercial truck chassis with custom cab). Something like a slightly used Prevost (though that's probably still $500k+, so won't help if you're priced out of traditional housing).