24" Apple LED Cinema Display vs. 21.5" 4K retina iMac Screen

That really comes down to opinion. Some people will prefer the larger screen, others the extra space that comes from the extra pixels.

I would suggest that see if can find one in a local Apple Store and see what you think of the screen yourself.

 

Don't most Apple store still have 24" displays in use with the Mac Mini and Mac Pro displays?

 

Can't remember last time I saw a screen in the Apple Stores, maybe outside the UK is different.

So by using the iMac in the Apple Store you can't tell if going to be able to use it? You won't see it side by side, but you should be able to see if you can work with the smaller screen/higher resolution combination.

 

I went down from a 30" 2560x1600 to the 27" Retina, and it's not good losing screen space. But I can't go back to a non-retina display so will stick with it until a larger screen appears. 24 to 21 is a bigger jump down, but if you like resolution you won't be disappointed. Why not go up to a 27"?

 

The 27" is superior in every way. But you can connect the 24" for additional screen space with whichever you get. I have a lower res 2nd monitor. I'd prefer it was 4 or 5K, but it's not though it is helpful.