Very difficult to make such a list. Many reported problems are with the appliances fitted which come from a very limited range of manufacturers. Design and construction methods have improved over the years (as evidenced by longer warranty periods).
Since 1992 I've only had 4 'vans - 3 British and my present Burstner and I have to say the present van has proved stronger and more reliable than the others but it's not perfect.
Also, if like a number of us, you are realtively handy and can fix things, then failures which would be a major problem to others become only a minor irritation such that the overall opinion of the same 'van would be quite different.
My major complaint is that the final inspection at works should pick up many more defects than it seems to, and that the dealer's PDI appears to be sometimes cursory to put it kindly. Although there should be remedies avaialble in the form of SOGA and Trading Standards, using either of these is not that easy for the average man having limitied free time, and Trading Standards staff do not, in my experience, have the knowledge to fully apprecaite the problems.