Hey there,
I thought this was a rather interesting topic and would pitch in my own thoughts and notions.
In my opinion, Like some others have said before me, The NOC deck from HOPC is a very nice deck of playing cards. It handles fairly well and the back deisgn is stunning, yet rather simple. I personally think that cards with mostly color and no design look elegant and divine. Other decks that are similar in this aspect would be: Wynns, Ace Fultons,Smoke and Mirrors,etc.
Pursuing this further, some of the decks I listed above don't handle the best. But, if you're looking for a deck that won't raise questions for your spectator
(For Example- Using a custom deck that looks rather different, like a black deck, or the Artisans for example)
I would suggest that you use a regular pack of bicycle playing cards. It looks the most familiar to the spectator.
Just my two cents
:: Yousaf