In ascending order of my preference
- VW bus or similar small Class B: Fun when you are young for a few days or a week when traveling, but way to small to full time.
- Truck and slide in camper: To be comfortable you will need a 3/4 to 1 ton truck
supporting a 10' plus unit. Lance makes a nice one. Cost of units could become prohibitive. Need to pull a toad or tour in a your large and high rig.
-Class B+ or Class C: Might work for a single person. Still requires a tear down for sight-seeing. A rental car is not an option in most areas I camp.
-5th wheel: Requires a larger truck (1 to 1 1/2 ton for most "livable' units. My 36' Travel Supreme is great, but is 36' and weights over 16,000 #. The combination is nearing 50' in length.
-Pull trailer: Nice set-up with easy hitching/unhitching. Most have few cabinets and little storage for a full-timer. The icon is an Airstream, which seem to hold value reasonably well. I would look at an Evergreen/Everlite unit, which is about 2,000# lighter than most competitors, and can be pulled with a half ton truck or a larger SUV. Also no wood to rot and reasonable initial cost. So new, that there are probably no used units available.
-Class A and Toad: Pull into a highway rest area, Sams Cub or campground and you are home. No need to unhitch, or step outside if it is raining or you are worried about the local environment. Plenty of storage both in inside and outside compartment. Plenty of cargo carrying capacity, toad towing capacity, availability of gas or diesel engines, etc. Connect/disconnect the toad in minutes, do traveling and come back "home". Units are cheap now. An older (1995-2000) high-end Beaver or Foretravel, or also nice slightly newer Newmar or Tiffin can be bought for around $55,000. Add a toad and tow system for a few thousand more and you have a home on wheels that will fit your every need. As an example, I also have an older Winnebago 34' Class A, gas unit, with 50,000 miles and a Suzuki Grand Vitara, plus all of the tow and braking equipment, all for under $20,000. It won't beat the diesels in a drag race up the mountain, but it will get there. I didn't know it was a race anyway!
By the way, I have had all of the above units, although in a slightly different order.
Good luck with your selection and keep it pointed down the road!