I own both as well. It's a really a tough call. Diner allows you all 3 balls to complete the objective to serve all 5 people. Taxi, you have 1 ball to pick up all 5 passengers....if it drains, you start over. To me, it just adds intensity to the game.
I personally still find myself playing Taxi more. I love the music and the callouts in Taxi.
IMO, the skill shot is more challenging and rewarding in Taxi.
I'm voting Taxi.....less expensive....and just as fun