I did look at the M series but my finances are pretty shot. It took me years before I was able to get a new TV and it was because of Covid unemployment benefits that I was able to save up enough to get this one. I looked at LG but when I finally got enough to afford a new set the model that I was looking at was discontinued. I require an analog audio output on the TV and needed at least 3 HMDI inputs plus a remote that has direct access to screen adjustments like zoom and wide and such as I have a lot of movies that are non anamorphic that require zooming in on the picture and also OTA TV channels at times don't broadcast widescreen movies properly they are postage stamped. I looked at Fire TV sets and none of them had a key for screen adjustment on the remote. My remote doesn't have one but a different remote model I bought for $5 off Ebay does have one and it allowed me to copy the command to my learning remote.
Some smart TV sets like Fire TV and Roku have dumbed down remotes and interfaces so if you need to change some settings you have to navigate several levels in menus to get there. If I didn't have a direct key to screen settings I would have to Hit the Menu button, Picture Mode, scroll down 8 clicks to Picture Aspect and click on it and then click till I get the one I want. With a direct key I click and the aspect ratio bar shows up and I move the cursor key and click the one I want. I can change picture settings like calibrated, calibrated dark, bright, vivid, Sports, Game.
A tv may have a great picture but if you have to jump through a dozen hoops to use it then it falls flat.
I do like Smartcast but don't have any comparison of other streaming setups like Roku and Fire and others platforms. I have used the cast feature with my phone once but since it has the apps I use to download movies from it and can cast my music to the TV hooked to my stereo it works with what I have.