I say the best taste would be mixing both Ketchup and Mayonnaise to get a mixture for all tastes either it's Dutch, French, Belgians or even your own taste.
For me I'm an old fashion guy and not trendy so I still dip fries in "LABAN" :P
Please know that the potato I'm talking about is a home made potato, so it's not crispy, in fact it's kinda saggy and that's what I call "Jordanian Fried" :)