Which is needed more, resolution(1080p/1440p) or refresh rate(60-144hz) for a 27-inch flat monitor? My purpose is web development (Python, JavaScript).

You only need 144 Hz refresh rate for enthusiast level gaming PCs.

I'm pretty sure the JavaScript runtime processes rendering tasks at roughly 60fps.

So probably more than 60fps won't help. If I'm correct.

I go for as many pixels/as high a pixel density as my eyes are comfortable with to maximise working real estate with the little physical space I have available. Until recently I was using 1440px24" diagonal, for simplicity I've gone to 2160px32" so I can treat the quadrants as 4x 1080p displays. Not ideal but working pretty well for me.

Unless you plan on reading 144 pages of code per second you don't need to worry about refresh rate.

In my opinion:
- 24" -> 1080p
- 27" -> 1440p
- 32" -> 2160p

Regarding the refresh rate, it's as @Fast-Nop said. If you're not an avid gamer, save your money and go for a regular panel.

@alturnativ also has an interesting argument. I personally went for a 21:9 / 34" 3,1440*1,440 to be able to work properly with two windows side by side (and sometimes 3 or 4).

I maintain that more than 60Hz refresh rate is marketing gumph for all but perhaps the most hardcore gamers.

Resolution on the other hand is definitely noticeable, particularly at 27". I'd go for that every time.

You may also find this tool useful for figuring out what might be comfortable for you (from a strictly size/resolution perspective): https://www.sven.de/dpi/

E.g. 1080p at 21" diagonal has the same pixel density as 1440p at 28"

Resolution hands down. 60 is more than enough for anything other than high speed gaming

For non-gaming use resolution wins. For gaming use Freesync wins.

I do think that there is a benefit of going beyond 60 Hz, however it really depends on you - some people think to notice a difference, some don't. Personally I overclocked my display to 80 Hz, but I only use that for gaming, since anything but 60 Hz (or a multiple thereof) makes for a very poor video experience (in the browser). YouTube will tear and tear and tear, so much that it makes me tear as well.

Thanks for your suggestion guys! Particularly for programming what panel should we for (ips, tn, va)? I am planning to buy only one monitor so what size would be ideal one ? Flat screen or curved screen ?

Curved is good, make sure you get the convex kind, vertical orientation. Those 10" guys they have on the Xerox Alto are beautiful.

@nanaji0133 ips would be the best in terms of color consistency at the edges due to the size of the monitor.

TN is a definite nope. You'll hate how colors start to change further to the edge. It's ok for a small screen but bad for a large one.

VA is okay but not as good as IPS in terms of color, but has a faster response compared to IPS

The difference between 60 and 120 Hz is very noticeable even in every day use like dragging windows and moving the cursor, but that doesn't mean 60 Hz is unusable. There are reasonably priced 27" 1440p 144 Hz monitors on the market. For 27", I would choose 1440p 60 Hz over 1080p 144 Hz because the advantages from the resolution are substantial. I would also recommend a flat IPS or VA panel for 27".