When I was a kid my stepfather had a 1973 GT Junior 1600...that was very special...
Maybe the Alfetta GTV V6 As in the one Roger Moore drove like he stole it in Octopussy) because of the busso... ? Or the early 2.0 spiders, as per The Graduate and Day of the Jackal?
As for later cars... I've owned four 156s 2.4jtd, 2.5V6 x 2 and two GTAs (one saloon and one sportwagon)
My first Alfa was a 156 v6....maybe less serious/more fun than a GTA..due to being able to rag a 2.5 slightly more safely..
166 3.0 is more special than all the 156es but none of these would be close to the best Alfas of the late '60s-early 1970s...which were cutting edge for their times...along with the Lancias of course Flavias, Fulvias etc.
Late 60's early 70s probably the best Alfa era... Spider, Guilia Sprint and GTA...AlfaSud...
Though maybe the very early Alfas were the best.... the one in Fleming's Moonraker maybe? The supercharged 8c?
https://en.wikipedia.org/wiki/Alfa_Romeo_8C