The XL compared to the XLII is a little less height. From a users perspective the XLII is a little quieter. I cannot tell the difference in ride or handling. The XL with the 12.7 L engine was the most economical coach produced and it was not unusual to get between 7.5 and 8 MPG consistently. With the XL you could get long range fuel which was 298 gallons which added to the economy because you could easily go 1800 miles and only needed toi buy fuel where it was the least expensive.
Skin damage was easy to repair if you had a big pop rivet gun. Windshields were cheap and easy to replace. All the tires were the same size and more readily available than the 365 tires. The dash lacked the good lighting of the XLII dash, but it was far simpler to service. Most fittings were compression fittings so you did not have to deal with aging push in fittings.
The XLII however has double pane glass so you don’t feel cold spilling down your neck from the windows on the side when you sit on the sofa. The tall front windshield combined with the larger side windows makes the coach feel larger and more open.
The skins on the XLII have been an issue on some coaches but it is likely Prevost has repaired those by now. If not no XLII should be purchased without a detailed skin inspection by Prevost.
All things being equal I would want the XL, but the smooth side panels of the XLII and the clean lines are far better looking.