Alison 545 is the transmission to avoid. I'm new too, but have figured that one out, lol. GVWR is a huge factor depending on your home state. In Maryland, where I live, if you have a MD drivers license, you cannot drive anything (even an RV) with over 26,000lbs GVWR without a special endorsement and taking additional driving tests or obtaining a CDL. 3/4 length busses (28-32 feet) newer than 1999 usually are over 26klbs and most full length busses over 34 feet are over that 26klbs limit if newer than 1995 or so.
I have also ruled out flatnose busses. Front impact VS any fullsize light truck or larger - you want a dognose if the driver wants to survive without lasting injury. Rear engine (RE) busses are the worst for driver safety but quietest. Dognose (busses with hood) are safest for driver and 2nd quietest - which is why I am looking for this style. Also, if you think about towing at all - then most folks avoid the rear engine models as they don't offer as good cooling as the front engine models.
I have also ruled out squared-coach mini's - they are built more like Winnebago's than busses. Round-coach mini's or round-coach medium truck busses are not 50% safer but more like 500% safer if T-boned or rollover.
(about 15 years of mixed fulltime towtruck driving, parttime towtruck driving, and volunteer EMS has led me to these conclusions. I have seen a Honda sitting on the queen bed of a traditional motorhome and seen larger vehicles bounce off the side of school busses.)