A lot depends on your particulars. What do you need to be comfortable? What are you willing to tolerate? Are you sure about those things?
I’m tall, so I definitely needed the tall Transit. (None of the other van models are as tall as the Transit.)
I’m a ham radio operator, so I wanted room for my ham-shack-in-a-box (and a few antennas on the roof).
I’m a recovering engineer, now a tech team development consultant. I work with all of my clients online, so I wanted a fold-away workspace for a laptop and extra monitor.
Whatever I chose, it had to be comfortable for my partner, so I looked for an extended body to maximize my options. I could build in a feature and, if it didn’t work out, I could redo it.
And I’m a miser, so I wanted a used van.
At the extremes of my vanlife fantasies, I envision boondocking for 14 days at a time in a national forest, so AWD would be nice, but that would be more expensive and kill the fuel economy. And I’ve seen plenty of dispersed camping along roads suitable for 2WD.
I also see a possible need for urban stealth camping (so I can, for example, attend a conference without paying for a hotel room).
The most common scenario would be to be touring the U.S. to visit family and exploring our wonderful world.
All this came together when I saw a diesel 2015 Transit on Craigslist, a Ryder rental truck in an earlier life: $25,000, with less than 80,000 miles.
I could go on to describe the design decisions around the galley, sanitation, hygiene, insulation, heating, and electrical, but that wasn’t part of the OP’s question, so I’ll stop here.
About that choice for the long body: I just added a trailer hitch last month. A couple of weeks ago, it scraped the concrete when I pulled out of a steep driveway. Without the hitch, it probably would have cleared just fine.