Yesterday I flew on both northeast shuttles to see exactly how they compare. I flew DCA to LGA on the US Airways Shuttle. I had Boeing 727-254 N912TS. Although the Official Airline Guide says it's a snack flight, we only got a bag of pretzels along with a whole can of soda. Service was excellent. In fact, last year I wrote a letter of commendation to US Airways regarding the outstanding service of a particular flight attendant that I have had on several occasions. We took off on time but were ten minutes late arriving at LGA because we had to fly in circles over Philadelphia for a few minutes.
I returned on the Delta Shuttle. It was Boeing 727-232 N412DA, in new colors. The snack was a basket containing an apple, crackers and cheese, a gourmet waffle cookie, and some mints. We only got a cup of soda, but the flight attendants came around offering refills. They were very friendly and cheerful. We arrived at DCA fifteen minutes early.
Both planes had blue leather seats, and both airlines allowed passengers to deplane through both the forward and rear doors. Delta's aircraft seemed to have slightly more legroom.
Overall, shuttle service is among the best there is for short flights. I highly recommend both the US Airways Shuttle and the Delta Shuttle if you want to experience flying like it should be.