C S.

It's 10:00 am on a Friday, and this is the number of restaurants I found available for delivery to my friend's address in NYC at this moment
Seamlessweb: 308
Grubhub: 261
--advantage: Seamlessweb

Seamless web's UI is much more useful.
I'm very big on reviews (obviously so are you if you are reading this.) Seamless web allows me to sort by stars and see how many reviews the restaurant has, a feature Grubhub does not have.
Grubhub does has yelp reviews as well as its own reviews, but what's the point if it doesn't link to yelp when you click on it?

Also when I go to the menu, the smaller font on seamless web makes me feel like I'm looking at a real menu, which is good.

Grubhub has the menu on the right bar with other restaurants still listed on the left bar. Why would you have take up valuable screen real estate when I've already chosen a restaurant? Also, because of the huge font, you have to scroll twice as many screens to see the whole menu, which is quite annoying.

Another advantage Seamlessweb has over grubhub is the most 'liked' and most 'popular' item boxes on the right, which is very useful when you are exploring new places to order from. I wish yelp would actually have a menu and the same kind of feature so i know what dishes to order when I eat in at a new restaurant!

Overall, seamless web the better site to order delivery from. There's a reason why all big banks use seamless web to feed their overworked geniuses.