Recommendations for TV (50"-60")?

i'm not sure exactly what your budget is or what your needs are since you were not very specific.

my parents recently purchased a samsung un50eh6000fxza 50 inch television http/www.samsung.com/us/video/tvs/UN50EH5000FXZA in december with my help and so far it has been very good. once we disabled 120hz, clearmotion and all the other add-on effects picture quality was excellent.

my own personal tv is a (now older) sony 40" bravia. while it might not be a completely top of the line model (even less so now that its 4 years old or more) its been very reliable and my own preference is to buy sony in the future when i need to upgrade. my second choice would be samsung for my own purchases.

generally i would advise to buy from sony, samsung or lg. they have the best quality sets. you can find parts for these, repairable.
brands such as panasonic and other well known brands other then the above are generally middling in quality and price. semi-disposable.
vizio has some nice offerings for the money however it is basically a disposable tv. if it breaks you are better off replacing it.
i would avoid emerson or any discount low end brands completely.

personally i would suggest avoiding the following, but please make up your own mind about them:

-120hz/240hz, the television fakes in (post processes) the extra frames making movement look smoother (less blurry). the tv still takes the same 60hz signal so it is not the same as 120hz computer monitors which can actually benefit from this due to their 120hz input. while this can look good for sports it also causes the soap opera effect which some people think makes television look plasticy and fake. if you hook up to a computer for gaming it also causes visible lag. the good news is that you can often disable 120/240hz in the menu (sometimes its called game mode)

-motionflow/clearmotion, similar to the above in terms of reasoning, also can be disabled.

-smart functions, while it may sound nice... and might be convenient for a short period of time, in the end its a useless feature. the included web browser is quite limited and hard to use and eventually will be outdated and useless. the apps are nice but will eventually become useless. the problem is that television manufacturers only support updates on their televisions for a relatively short period of time. once your version of the apps becomes incompatible with the service.. they might not function correctly/at all. again, you dont have to use them or can upgrade to some other device which has these functions in the future if needed. also, since you have a roku you dont need smart functions as you have this already.