Which is better for movies?

The Samsung HW-Q990H. Its 11.1.4 layout and four up-firing channels give more precise overhead and rear placement, and the dual 8-inch subwoofer handles deep bass with less strain.

Which one pairs better with my TV?

It depends on your TV brand. The LG S95TR's WOW Orchestra works with LG OLED sets, and the Samsung's Q-Symphony and SpaceFit Sound Pro work with Samsung TVs. Mixing brands loses those features.

The Samsung has the better track record. Its 4.8 rating from 520 owners shows few failures, while LG owners report subwoofers that would not pair and one unit that died and needed warranty repair.

Is the LG worth stepping up to over the Samsung?

Only if you own an LG OLED and value WOW Orchestra. Otherwise the Samsung offers more channels, more streaming protocols and stronger owner satisfaction for a comparable flagship class.

Do both include rear speakers and a subwoofer?

Yes. Both ship as full systems with a wireless subwoofer and wireless rear speakers, plus a wall mount bracket and remote.

Can I stream music to both?

Both support Wi-Fi and Bluetooth. The Samsung adds AirPlay, Chromecast built-in, Spotify Connect and Roon Ready, so it fits more streaming setups.

LG S95TR Soundbar vs Samsung HW-Q990H Soundbar

The Samsung HW-Q990H is the stronger pick for most people. It has a true 11.1.4 layout with four up-firing channels, a dual 8-inch subwoofer and far more streaming options, and its 4.8 rating from 520 owners is much more consistent than the LG's divided 4.3 from 73. The LG S95TR is a solid alternative if you own an LG OLED and want WOW Orchestra, but owners report more connection dropouts and subwoofer pairing faults.

Choose the LG S95TR if you own an LG OLED B4, C4 or G4 and want WOW Orchestra to blend the bar with the TV's own speakers.
Choose the Samsung HW-Q990H if you want the most complete surround package, wider streaming support and the more proven reliability record.

Prices

LG S95TR Soundbar: $698.00 at Greentoe (checked today)
Samsung HW-Q990H Soundbar: $957.67 at Greentoe (checked today)
Difference: the LG S95TR Soundbar is $259.67 cheaper than the Samsung HW-Q990H Soundbar today