Jim,
If not already, I encourage you to peruse an article from WPC News dated May 1982, found here:
https://www.web.imperialclub.info/Articles/61-63WPC/index.htm
You will find the model years were very nearly identical in terms of chassis and powertrain, with '63 being really the last Exner styled Imperial. Though notable changes did occur in several areas: 1962 received the aluminum torqueflite transmission, a new lighter, high torque starter, 1963 saw the 'Park' lever added to the transmission (earlier models relied on the parking brake); all years were pushbutton accentuated. The interior amenities/options were basically the same though 1961 was the last year of swivel seats. All three years had the cool electroluminescent dash, ditto the 'flite-sweep' decklid option. WWW tires went away in '62 I believe. The 413 CID engine was standard across all three years with a slight drop in HP after '61. (350 to 340).
It may just come down to your personal preference as to what model year suits you best as it's practically impossible to state one year was materially better than the other. I like the '61 because of the FINS!!! Others may like the less dramatic styling of the '62 or '63. Hope this helps and good luck!
Greg