I would like it to be under $350, and between 50 and 55 inches. I really don’t want to add a sound bar, so good internal speakers are a must. Any suggestions?
Curious to see what you come up with. I did a bunch of TV shopping last year, and while I have a sound bar, I did want to test the internal speakers too just because why not. And my experience was that they’re all pretty abysmal sounding.
I’d agree with this. It’s really hard to make a speaker that is .5" thick and handles 10W+ of power.
I want to note that when it comes to internal speakers, how you mount it is likely to make a big difference. If it’s going to sit on a stand on a desk/table/tv stand or you mount it in a wall mount, you’re going to get very different sounds out of bottom facing speakers.
For the record, before the last round of tariff debates, my wife and I got this from Costco for a wall mounted TV, it’s in your price range (if you can find it in stock) even at the larger size:
https://www.costco.com/hisense-65"-class---qd6-series---4k-uhd-qled-lcd-tv.product.4000272280.html
I have a soundbar I could attach but the sound was good enough (NOT the same thing as good) that I didn’t bother. Then again, this is mostly for having movies running in the background when we’re doing other things, we don’t do much dedicated movie watching at home.
It will be on a stand on a table, not mounted on the wall.
How do you define “good”. When I was looking for a 55 inch TV earlier this year I didn’t want a soundbar, but I couldn’t find any TVs, let alone a 4K TV, that had even decent sound, let alone “good” sound. I bought a sound bar and I’m glad I did. If you can find this unicorn, let me know what brand and model you decide on. I want to listen and hear how good the sound is.
By “good” I mean better than the usual sound systems found.
The one I listed I’d qualify as “good for the usual sound systems” but NOT better than the usual sound systems, sorry. 
ETA - your definitions may vary, if you want, I’ll take a few second video of something playing on my system and link it or send it to you in a PM, though that’s another layer of compression and possible crapification if you want to judge for yourself.
Please note that we do not live in a large house-just a medium sized apartment. It doesn’t have to be loud enough for the neighbors to hear, but I wouldn’t mind a nice, clear sound.
Get yourself a pair of these and put them on either side of the TV. They’ll provide superior sound - better than any TV speakers.
Not looking for external speakers.
I think they’re mostly abysmal because the assumption is that anyone buying a large-screen TV will have an actual home theater audio system. But it’s not necessarily difficult to build good sound into TVs. Sony OLED TVs use something that Sony calls Acoustic Surface Audio where the entire screen acts as a speaker, and the latest models even use advanced audio processing to locate the sound in precisely the right location. But Sony OLEDs may not be in the OP’s price range.
For example, this one is 55", high refresh rate (144) and has 20w speakers for $329.99. Any others with the same or better sound? TCL 55" Class - Q77 Series - 4K UHD QLED Smart TV - Allstate 3-Year Protection Plan Bundle Included for 5 Years of Total Coverage* | Costco
Yeah, I made the mistake of looking at some LG OLED tvs and ended up spending much more than I originally intended but the effect was mesmerizing. And yeah, it has much better sound than the regular LCD panels and I do not know how. Whole thing is just millimeters thick.