opinions

I don't think there is too much to think about...they probably are both good for the job. I personally would probably go for the NAD, but its not a huge decision.

Have your AR's been restored...foam surrounds and caps? You want to get the most out of them and make them easier to drive. The AR is not an efficient speaker.

The NAD is an efficient amp and puts out more power than its rated 30 wpc and may be able to drive the 10" woofers w/o any difficulty.
The Sansui 666 is from the 70s and would make for a nice vintage system. If at all possible, try and audition the Sansui with your speakers.

How large is your room?

Which NAD 3020? The classic vintage one or the new Hybrid Digital?

I think its safe to say its the old version for a few reasons. 1. Its been serviced. 2. He's comparing it to a different vintage amp that has been serviced, as well. 3. There really isn't 2 versions of the amp. 3020 is the vintage NAD, and D3020 is the new digital amp. Different model numbers.

yes my speakers have been restored and my room is an average sized living room