Which is better for console gaming?

The TCL QM6K. Its 144Hz panel, Game Accelerator 240 and four HDMI ports give more headroom and connections than the Roku's 120Hz panel and two ports.

Which has better built-in sound?

The Roku Pro Series. Its side-firing Soundstage speakers with Dolby Atmos are a clear step up from the TCL's 2.1 ONKYO setup, though a soundbar still beats both.

The TCL QM6K has more brightness headroom for HDR highlights, though it trails TCL's own brighter Mini-LED models. The Roku holds its own but is not a light-cannon set.

Is the Roku easier to use?

Yes. Roku OS is simpler and faster to navigate than Google TV, which matters if several people in the house share the TV.

Neither has a documented reliability edge. The TCL has a much larger review base, while the Roku's smaller sample still rates slightly higher.

Should I step up to a brighter Mini-LED set?

Only if you watch a lot of HDR in a bright room. The QM6K is already a strong value; brighter models cost more for a modest gain.

TCL QM6K QD-Mini LED Google TV vs Roku Pro Series OLED

Buy the TCL QM6K if you want the most picture per dollar and a 144Hz panel for gaming. Buy the Roku Pro Series if you want a simpler interface and a design that sits flush to the wall. The TCL wins on brightness headroom, native refresh rate and HDMI inputs; the Roku wins on sound and ease of use. Owners rate both highly, but the TCL has far more reviews behind its score.

Choose the TCL QM6K if you game on a console or PC and need 144Hz, VRR and four HDMI ports.
Choose the Roku Pro Series if you want the Roku home screen and a TV that mounts nearly flush.

Prices

TCL QM6K QD-Mini LED Google TV: $427.99 at Amazon (checked today)
Roku Pro Series OLED: $649.97 at Amazon (last seen Nov 8)
Difference: the TCL QM6K QD-Mini LED Google TV is $221.98 cheaper than the Roku Pro Series OLED at the latest prices (Nov 8 and Nov 9)