We have 3 hour races in 2 classes in LFS GT, 2nd class being XFR and UFR and we are very equal. UFR is the same or slightly better in braking, acceleration and cornering, and XFR is little faster at the end of longer straights which makes it pretty much equal overall. 1 hour stints for both cars are no problem at all (R3 or sometimes even R2 on the front), in fact we changed only front tyres sometimes, but we have not been brave enough to try 1h 30minutes stint in either of the cars, so we can't tell for sure which car is better on the tyres, though we suspect UFR is. Theres a new season in Czech league going on now that uses this class, so that could be looked too. I didn't follow it, maybe Chaos could give us a little report.
Being the lighter and more nimble car I prefer UFR, same thing for XFG. Its just more fun to toss around smaller and lighter car.

XRG is there for those who really hate FWD and those people usually can handle it just fine and be perfectly competitive.

Sure, some tracks favour one car, some another, but overall these classes are well balanced and no car is obvious winner, there's a car for each different prefference. Difficulty in handling is also driver's choice.
