In no particular order since I love them all, my 10 faves would be:

Burnout 3

F-Zero / X / GX

Super Mario Kart

Top Gear

Forza 4

Diddy Kong Racing

Waverace 64

Extreme G III

Road Rash 64

Need For Speed III Hot Pursuit

Honorable mentions:  Star Wars Episode 1 Racer, Top Gear Overdrive, Beetle Adventure Racing, Destruction Derby 64, F1 World Grand Prix (N64 had alot of great racers!).

1. Forza Motorsports 4
2. Forza Horizon 2
3. Burnout Paradise (own it on PS3 and 360)
4. Gran Turismo 4
5. Forza Horizon
6. Gran Turismo 6
7. PGR 4
8. Midnight Club: Los Angles Complete Edition
9. Need For Speed Most Wanted (2012)
10. Gran Turismo 2

I'm pretty sure that Forza Motorsports 6 will knock one of those games out of my top 10.

I still think Takedown is the better racer (and definitely much better crash game) but I have spent a lot of time with Paradise as well. I completed the whole game again after it got trophy support, one of my first platinum trophies, and doing stunt challenges online was tons of fun. It had awesome support (free motorcycles!) and big surf island was a great addition. I later got the game again on Steam in a sale, looks lovely in 1080p60.

My top 10:
1. Forza 4
2. Mario Kart 8
3. Forza Horizon 2
4. Super Mario Kart(SNES)
5. Gran Turismo 4
6. Diddy Kong Racing
7. F-Zero GX
8. Ecitebike(NES)
9. Burnout 3
10. Gran Turismo (PS1)

Underrated gems that I love:
1. Mario Kart: Double Dash
2. Extreme-G (both)
3. Test Drive Le Mans
4. Sega Rally
5. Ecitetrucks

Overrated games that aren't that big deal IMO
1. Crash Team Racing
2. Gran Turismo 5 and anything else published by Sony after the PS2.
3. NFS Underground and Pro-Street. (All of them)

1. Gran Tursimo 3

2. Burnout Revenge

3. Midnight Club 2

4. Crash Team Racing

5. Gran Tursimo 2

6. Midnight Club 3

7. Mario Kart 64

8. Need for Speed Underground.

9. Jak X

10. Test Drive 4

6) Need for Speed: Most Wanted (PC or whatever)
5) Mario Kart 7 (3DS)
4) Diddy Kong Racing DS (DS)
3) Mario Kart DS (DS)
2) Split/Second (what little I played, PC)
1) San Fransisco Rush, 2049 (N64)

WE NEED A SEQUEL TO RUSH PLEASE

1. Forza Motorsport 4 (Xbox 360, 2011)
2. Forza Horizon 2 (Xbox One, 2014)
3. Rallisport Challenge 2 (Xbox, 2004)
4. Test Drive Le Mans (Dreamcast, 2000)
5. Forza Horizon (Xbox 360, 2012)
6. Forza Motorsport 5 (Xbox One, 2013)
7. Diddy Kong Racing (Nintendo 64, 1997)
8. Mari Kart 64 (Nintendo 64, 1997)
9. Project Gotham Racing 2 (Xbox, 2003)
10. Moto GP 2 (Xbox, 2002)

-> I suspect that Forza Motorsport 6 is about to claim my top spot.

1. F-Zero GX (GCN)
2. F-Zero X (N64)
3. Mario Kart: Double Dash!! (GCN)
4. Mario Kart 8 (Wii U)
 5. Mario Kart 64 (N64)
6. Diddy Kong Racing (N64)
7. F-Zero GP Legend (GBA)
8. Mario Kart DS (DS)
9. F-Zero Climax (GBA)
10. F-Zero (SNES)

Excuse me for the lack of variation of game series and for the excess of EA games.

1. Gran Turismo 2
2. Midnight Club 3: DUB Edition Remix
3. Need for Speed Most Wanted (2005) (BMW M3 GTR ftw)
4. Need for Speed ProStreet (Criminally underrated)
5. Gran Turismo 4
6. Driver San Francisco
7. Gran Turismo
8. Midnight Club Los Angeles
9. Need for Speed Carbon
10. Need for Speed Hot Pursuit (2010)

Well Paradise is the only Burnout game I ever played got it first on the 360 (physical) and then bought it again on the PS3 because I like it and it was super cheap $2.99 and it came with all the DLC (digital).