Here's final update to the rankings for December and 2017 as a whole (five days since last update):
First the monthly rankings:
Nintendo Switch (grey): #6 (—)
Nintendo Switch (neon): #10 (↓1)
PS4 Slim Battlefront II bundle: #14 (↓1)
PS4 Slim 1TB standalone: #28 (↑2)
XBO S Forza Horizon 3 Hot Wheels bundle: #31 (↑2)
Xbox One X: #36 (↓2)
New 2DS XL (black & turquoise): #46 (↓7)
PS4 Pro: #53 (↑3)
The SNES Classic Edition was previously ranked #22, but has disappeared from the rankings. It appears to have been moved to the Computer Software section on Amazon for some weird reason. Oh, and Mario Kart Wii finished at #81 for the month.
And now the yearly rankings:
Nintendo Switch (grey): #8 (—)
Nintendo Switch (neon): #14 (—)
PS4 Slim Uncharted 4 bundle: #22 (↓1)
PS4 Slim 1TB standalone: #37 (↑3)
XBO S 500GB standalone: #48 (↑1)
PS4 Pro: #64 (—)
Xbox One X (Scorpio Edition): #73 (↓1)
PS4 Slim Battlefront II bundle: #82 (↑1)
Xbox One X: #83 (↑1)
The SNES Classic Edition was ranked #36 in the yearlies at last update.
I'll have the January thread up shortly.
Looks like Switch should win the month comfortably but who knows, NPD will be interesting.
NPD will show how useless amazon ranking are.