I've recently undertaken this project for my folks new home and after listening to a few in-store decided that "all in one soundbars" without a separate subwoofer are a waste of time.
Like you, they didn't want the complexity of a AV separates system with 5.1 speakers and a receiver, so I eventually settled on an affordable Sony HT-RT3 5.1 soundbar.
It has true 5.1 with L/R+C in the soundbar, a dedicated sub that isn't flashy or obtrusive, and two wired surround speakers for which I ran cable around the edge of the room under the carpet, terminated at a terminal block on the skirting board behind the sofa and ran up the side-table legs either side of the sofa. They could even be hidden in the corners of the room at floor level, tbh. The amp, HDMI ARC connector and SPDIF connections are in the subwoofer, so you do need to place that somewhere near the TV (or run long cables). Also, all the connectors are proprietary plastic plugged things, so you'll need to modify them if you want to increase the cable length, but this is true of almost all soundbar/HTIB solutions.
As far as sound quality goes, it's as good as any other sub-500 plastic soundbar solution; Neither the pinnacle of fidelity nor punchiness but even as an audiophile I think they get 80-90% of the way there for minimum financial outlay and do so whilst being pretty minimal.
I've not listened to all the options on the market, but after listening to half a dozen or so at wildly different price points I realised that the plastic-cabinet, small-driver soundbars all suffer the same flaws in audio quality (a lack of clarity and definition in the midrange crossover between sub and ~2" drivers in the soundbar) so buy a setup that looks good and be happy with the compromise in sound quality. I had to remind myself that just because I've trained my ears to tell the difference between $500 and $5000 speakers doesn't necessarily mean that most people care, as long as the bass is deep, the treble is crisp, and their music sounds okay.
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