Space Giraffe for me. I know it's a tempest remake, but because of the intense graphics, importance of audio clues and scoring system, once you get in the zone you have this sensory overload that I've never experienced with any other game before. It's like your brain goes to another dimension.
Also Outrun 2 has no peers in terms of arcade racing. When the servers had people on, it was so much fun cruising round the 15 course mode. such a chilled vibe driving round the sunny levels with magical sound shower blazing away, and people didn't take it super competitively so you rarely had to put up with bumholes spoiling the race. Good fun all round.