If dialogue clarity is the main goal, go for something with a dedicated center channel and a mode that boosts voices. Between the two you mentioned, the Samsung HW-Q600C is the better pick. It’s a 3.1.2 setup with a dedicated center speaker, Samsung’s Adaptive Sound feature that makes speech easier to hear, and it will work perfectly fine over ARC even without eARC. The HW-B750D is okay but not as clear or well-tuned for voices. Other options worth checking out in your budget are the Sony HT-G700, Yamaha SR-C30A or SR-B30A, and the Polk Signa S4, all of which do a great job with dialogue. If you go with the Q600C, make sure Adaptive Sound is turned on and, if needed, increase the center channel level a bit to make voices stand out even more.
Wow is known to be terrible and worse than not using it !
Beyond that all LG soundbars have awful reviews, even for there price !
I’d go Samsung q600c at this price range … entry level Dolby atmos with great reviews
It was the Q600C. Wasn’t even half the price of the Q990D when I first looked at it however it dropped from over £500 to £279 here when I bought it. Genuinely thought I’d bought low end for the price but been blown away by it.
Why not just get some speaker wire?
I have the Q600C, w/ the SWA-9200s rears, and the wire it comes in the box with is 6 meters ~19.7 feet. If that’s too short, I can’t imagine it would be too expensive to get a roll of some equivalent-sized speaker wire - and as a plus you could get it in whatever color works best, so you can hide it easily in your space.
If hiding the wire is your concern - this wire is small enough, that you could honestly probably tuck it in the little gap under your baseboards, and hide it that way. Or run it along the little edge at the top of the baseboard, tacked down with a couple dots of silicone, and then painted to match the wall color.
Top picks (all true Atmos + wireless sub, ≤ 42”)
• Vizio M-Series Elevate M512e-K6 (41.38”) — 5.1.2 with included rears + up-firing in the bar. Killer immersion per dollar. 
• Samsung HW-Q600C (40.6”) — 3.1.2 with up-firing drivers, eARC, and works with Samsung Q-Symphony (your Q90T supports Q-Symphony with compatible bars). Great if you want the TV+bar to play together. 
• Polk Signa S4 (41.2”) — 3.1.2 with two dedicated up-firing heights; simple, slim, and dialog-friendly. 
• LG S75Q (35.1”) — Compact 3.1.2 with upward-firing height channels, HDMI eARC, Dolby Vision passthrough. 
• Bose Smart Soundbar 600 (27.3”) + Bass Module 500 — Small bar with 2 up-firing drivers; add the sub for real low-end. (Sub is separate.)
AboveAverageAlias
