After reading the OP again there is no mention of engine or different options.I think he is asking what single year/s model is most sought after by the general public.I know its hard to seperate personal opinon.So heres my view of what I think the OP is asking.
1 general public:Nearly everyone I tell I have a 70 dart says "I knew a guy with a 340 swinger and it was the baddest car I ever seen/been in).So from my experiance the 70" is the most reconized year,removing the 340 aspect the car is still known.
2 collectors/car guys:Most car guys apperiate the earlier years more than the average guy and the 68" stands out from the "hemi" option.
What I'm getting at is the general public sets the disreablity and value of cars not car guys.For instance look at the charger 68-70 had very few changes but the 69 is the wholy grail of muscle cars because the general public seen it on "THE DUKES OF HAZZARD" and it became an icon and really jump started the mopar craze,before that you could still get a 70 hemi cuda without donating a few internal organs.
So trying not to be biased I think the most sought after year is 1970 in the swinger and 71 in the demon,OP didn't specify which dart.
