Hard Drivin for being a tech marvel at the time is an argument, but picking it over stunts and trackmania isn't something I'd agree with.
Outrun 1 is fun, but 2 set a drifting standard few games can live up to
If anything, TDU2's MP stuff should get the edge over 1 for being a forza inspiration, even if the handing gets squirrley mid-game
Most Wanted earned its spot over underground 2: A way better map, cop chases, and exotic cars made it wow worthy over underground.
Street rod is a deep cut, but I am unsure of the quality of said game to note the high position on the list
Hot take but GT2 is the most gran turismo-y of the series with an even better soundtrack than 3 and a billion niche cars to put big ass turbos on
Games worthy of said list:
Trackmaina (the original one) or nations for being a free taste of said game
Rush 2049 for nailing the arcade formula and wings!
NFS Porsche Unleashed: every Porsche car in one game with a career mode through the years was a peek of things to come with underground, the soundtrack ruled, and it was the game for those who despised the whole underground thing
PGR2 (I haven't played the 360 ones yet): Sumlime semi-sim racing with a load of car groups
Rallisport Challenge 2: Sumlime semi-sim rally racing with a load of car groups, only matched by DiRT (also noteworthy) or Forza Horizon years later