Good Enough

There are no "Good Enough" displays for macOS.

They are either "Great" or "Meh".

Here are 3 correct resolutions for macOS.
1. 21.5" with Full HD or double of that 4K.
2. 27" with 2,560x1,440 or double of that 5K.
3. 32" with 6K.

So what are the options?

For option #1, there are lot of Full HD 21" monitors, that work on HDMI and some of them support USB Hubs. But come under "Meh" category. There is no 4K monitor @21".

For option #2, there is LG UltraFine 5K, which costs whopping 1L and has lukewarm reviews and stand that wobbles.

For #3, this will set you somewhere between 6~7L and has a stand that doesn't wobble. This is the "Great" category.

There are lot of 4K 27" monitors, with good quality screen and feature set, so what goes wrong when you use one of these?

Well, when you hook it up, macOS decides that it is best to run at Full HD resolution, it would put two pixels for each pixel. Computationally this is the simplest thing to do. But when you do this, you are effectively getting same amount of real estate of a 21.5" screen which is running at Full HD.  

Luckily a lot of things in OS are resizable (dock). But there are assets that can't be resized (menu bar).

You can also run the display at "sampled" rate, where display is rendered at 2,560x1,440 and then blown up to run at 4K resolution. This is a good idea, but comes with a cost of rendering sampled screen.

So what is the right compromise?

1. Get 27" 4K and then run it at 2,560x1,440. There will be performance hit. Hopefully your computer can handle additional load.

2. Get 24" 4K. Things will look big but not too big. You can adjust resolution and placement to make it easier on eyes. Now, there is only one gaming monitor available in this category, which, doesn't support USB Hub [1].

3. Kick the can down the road. Get Full HD monitor at 21.5", it will be rendered natively, no sampling issues, cheap, lots of options. It will be easier to replace it when better options come along. But you will have low resolution screen.

When I had to chose four months back, I went with the third option, at the time it seemed most sensible. But as I see Big Sur screenshots and its emphasis on rounded corners, I think it would be better to go with 27" at 4K.

[1] USB Hubs in monitors are underrated, they reduce need for dongles and keep setup clean.