Consider most of people already gives what they like and also me have variety of interest (likes Rally, Endurance racing, Open wheel, Closed circuit, Street races and so on), maybe I'll go with Tokyo Xtreme Racer (and its spin off Drift) series. To me Genki much more than a game but rather a love letter to these genre (they even go down with consulting with street racers, incorporating them in game, and make short documentary about them!).

(Excuse me for going a little bit on culture) First the main elephant, the Wangan racing genre. back then (even to this day?) this sub-genre of racing is niche as IIRC this racing scene mostly around Japanese and traced way back in 80s and early to mid 90s during Economy bubble era. Everyone had a lot of cash to spend their money and guess what? those city people spend it on (illegal) street racing and the infamous one where they raced on highway networks. You got japanese tuners also actively participating on these kind of activity even the infamous one! Like owner of RE-Amemiya, Abflug, TOP SECRET, Auto TBK, MCR and so on, now coupled of that with infamous exclusive Mid Night Club, you get the idea of why these people seeking thrill of moving fast on this highway roads. For Touge scene and sub-genre, I think you guys all know very much as it's more popularised by kind of Initial D and such.

Back to the game. back then you can't find a almost 1:1 recreation of Shuto highway network in a game. On Tokyo Xtreme Racer 1 (Dreamcast) you have almost 1:1 recreation of C1 loop portion of Shuto highway which is well made and still hold up to this day even with decent car roster. Tuning in this game is fairly deep and necessity to gain upper hand on higher stake, you have to make sure your gear setup suited to the portion of highway you're currently run, running on Wangan Bay route isn't the same as running on C1 Loop or Shinkanjo area. Tokyo Xtreme Racer 2 (on Dreamcast) brought Wangan Bay route and Yokohane road into the menu and so the highway network almost fully(!) complete, this time they brought more selection to the cars and gives you freedom which car you want to start your adventure to become one of the fastest highway racer. Tokyo Xtreme Racer Zero somehow a port of TXR 2 on PS2 which add several new rivals and new cars exclusive to PS2. Tokyo Xtreme Racer Zero-One (3 on the West) brings licensed cars and 2 other city like Nagoya and Osaka but at cost of reduced cars (still interesting selection).

For both main series and its spin off Drift series that distinguishing themself with other akin to Need for Speed is the RPG element and roguelite that makes every playthrough can be different. You can start the game using Kei cars class, you can start with bigger luxury cars, or you can just start with sport coupe cars just like everyone else. Your car is half of your strength, you need to couple that with car setup and your skill to conquer the road to become one of the fastest. Another interesting bit is that each Rival has these small bios about them which gave them little bit of personality. To me those what makes it feel more raw and engaging for use who likes the genre and culture around it (becasue back then these street racers come from variety of background, you can have your ordinary young adult up to businessman member).

Nowaday Wangan genre have their spot filled with Assetto Corsa with Shuto Revival Project (SRP) map and even with "No Hesi" (western equivalent) server and you have standalone game such as Night-Runners.

While Genki confirmed they develop new Tokyo Xtreme Racer, I have mixed feeling on it afraid that it turn become something like C1GP where they playing "safe" and becoming more into legal area turning the highway into something like sanctioned race event akin to Tokyo Expressway/Special Routes map in Gran Turismo. Wangan racing without traffic and heavily modified cars kind of feel off.

Fun fact: Genki help Namco develop Wangan Midnight in its early day even on PS2 game they reuse TXR0 game engine, and then Namco do it themselves and turn it into arcade game (Wangan Midnight Maximum Tune series).