This chart of the Top 5 Roleplaying Games (hobby channel) reflects sales in Fall 2017.  The charts are based on interviews with retailers, distributors, and manufacturers.

These bestseller lists are from ICv2's Internal Correspondence #93:

For the lists of the bestselling Collectible Games in the hobby channel, mass channel, and overall, click here.
For the bestselling Board Games in the hobby channel, click here.
For the bestselling Card/Dice Games in the hobby channel, click here.
For the bestselling hobby channel Non-Collectible Miniature lines, click here.
For the bestselling Roleplaying Games in the hobby channel, click here.

For info on how to get your copy of the ICv2's Internal Correspondence #93, with the full market reports and size estimates, bestseller lists, and reviews, see "ICv2 Releases 'Internal Correspondence' #93."