Is the TCL QM751G worth it over a cheaper 98-inch TV?

Yes, if you care about contrast. The QD-Mini LED backlight with local dimming gives deeper blacks and brighter highlights than standard LED big-screen TVs, which is the main reason to pay more.

How does it compare with TCL's QM8 series?

The QM8 is TCL's flagship Mini LED line with higher peak brightness and more dimming zones. The QM751G sits below it and costs less, so it is the better pick if you want a large Mini LED screen without flagship pricing.

Does it support Dolby Atmos?

Yes. The TV supports Dolby Atmos, though the built-in speakers are limited by the slim cabinet. A soundbar or AV receiver will deliver the effect far better.

What smart platform does it use?

It runs Google TV, with hands-free voice control built in. That gives you Google Assistant, Chromecast and the usual streaming apps.

Will it fit on a standard TV stand?

A 98-inch set is very wide and heavy. Check your stand's width and weight rating, or plan to wall-mount it on a suitable bracket.

Is it good for gaming?

It has the picture quality for console gaming, but check the HDMI inputs and refresh rate for your console before buying. Serious gamers may prefer a set with higher refresh and dedicated gaming features.