The Bando aftermarket belts are a little different than the dealer ones. Usually the non-ribbed side of the aftermarket Bando belt will have a smooth rubber layer instead of the "fabric" type material that is used on the dealer belt.
I usually see the dealer belt last 100k+, but the aftermarket Bandos last 2/3 of that time. The aftermarket ones also stretch more and will require more frequent retightening on applications without an automatic tensioner.
But for the price, you cannot beat the aftermarket Bando belts.