The bad reputation about WASR's primarily came from the earlier ones. The newer ones available now are actually quite nice. They're rough, and have surplus parts, but they're very solid, reliable guns. They're not lookers, but they're good shooters. Many of them have threaded barrels, as well, to allow you to install muzzle brakes and hiders. They're a very good deal for the money.
As for the Arsenals, they're a different animal. They're made from new-production Saiga rifles, made with new parts, modern tolerances, etc. They're fitted with premium parts and features. Both WASR's and Arsenals will be equally reliable, but the Arsenal is just a much more polished example.
Bottom line: if you want it to shoot good and be fun, and don't care as much how it looks, go WASR. If you're willing to pay for the better fit and finish, go Arsenal.