Great West Vans is out of business... don't expect them to be back as their bank closed them. There may still be negotiations going on, but...
Leisure Travel no longer makes any B Class units... only small Class C units. They are top quality, but very expensive. I suspect that they may never be able to start producing their B's again... and they were all on Sprinters. (their Chevy Class B was stopped some years ago now)
Pleasureway only makes small Class C units and one Promaster conversion.
Your choice is either Roadtrek or Sportsmobile.