I decided to check out the RouterOS nightly build and couldn't connect using Winbox 3. It only worked with Winbox 4.
That’s a bit of a forced requirement, don't you think?
A bit but it should be expected. Think that we have to grit our teeth.
oh no guys, hes getting forced to use a better thing, for free and its way easier to do his job with it too! How dare they!!!!!!!!!!!!
As our good old chisels and hammers could stil be usable.
Have you seen piramids or St. Peter's Basilica in the Vatican size buildings built with contemporary tools?
And here is JdeBP take on "legacy":
https://jdebp.uk/FGA/legacy-is-not-a-pejorative.html
Winbox 4 has been good to me. Did not have any issues with it.
Fair to say it matured enough for my use case.
You'd rather stay on Winbox 3? If so, why?
The older you get, the harder it is to accept changes.
There was a time when keyboard meant keyboard and phones were used to talk, not to make photos 
b e c a u s e i t l o o k s b a d, t h e m a r
t e x t d o e s n o t f i t i n t o
That's fixable. Just change the Font.
Click the cog icon on the top right, go to settings and set your font there.
v3 is imho still cleaner and easier to read.
v4 looks modern and if someone is looking over your shoulder, it gives you a better feeling that you dont fiddle around with something that looks like a blast from 1998. The jumping windows in v4 seem impossible to fix. I never asked for a v4 but we have to accept the move to v4. Its like the XP to Vista transition, we all could still happily use XPx64, but M$ decided (for us) Vista was the way to go. Same here, v3 works, is reliable, slim, easy to read... but Tik decided for us, v4 is the way to go.
Personally, I got used to v4 after a few weeks. But never go back, make a hard cut. From now on only v4. But its still way better than the html/browser-cocnfig stuff like SonicOS (Sonicwall) has. You have to look for a Policy-Object, close the firewall-rule (you have 95% finished), go back an create from scratch... Even v4 is better.
As you are using Windows, change the font, scaling and spacing setting and you'll get the same density as WinBox 3. If you want to match WinBox 3, set font to Microsoft Sans Serif, Table row height 1, Global zoom 92% (which sets the two other factors to 92%) too.
Or if you prefer something more modern (looks like Windows 10), but still with good density. You can try something like this.
Yes, I prefer Winbox 3! For VARIOUS reasons.
I will mention 2:
The first is that I usually open 40 or 50 winboxes, one for each client's equipment, when I'm scanning the client's network to make improvements.
With Winbox 3 I could do this easily with a computer with 8GB of DDR4 RAM and a not-so-new CPU.
With Winbox 4, with a very respectable computer, this becomes almost impossible to do.
The second is that when I open Winbox4, it takes more than 15 seconds to read something before it starts showing something.
Combine the second reason with the first and chaos is done.
But there are several other reasons!
I still say that the Winbox doesn't have to be made for having a 32-inch curved monitor and working in an air-conditioned room.
It has to be done for the guy who opens his notebook on the hood of his car in front of a street shelter having to recover from a massive outage in the 3pm sun of a tropical country.
Fair points on both sides. I run into the resource hunger too when I've got a dozen sessions open at once, v3 barely noticed it. That said, once I bumped the zoom down and switched the font like CGGXANNX suggested, v4 got a lot closer to the old density and became usable for daily work. Still hoping they tighten up the startup time and memory use before dropping v3 support for good, especially for people managing gear in the field on modest laptops.
Have I been away for 6 months and missed something? Everyone is still on their WinBox 3 vs WinBox 4 Holy War as expected, but OP is on RouterOS 7.25 and I never noticed this version being released ...
No, he tried latest nightly built and inferred that next coming 7.25 will be Winbox v4 only because the nightly built didn't work with v3.
Even if OP is not right and it is is simply a glitch in the nightly build, if it won't be 7.25, it will be 7.26 or 7.27.
The good Mikrotik guys:
Ah, thanks for explaining. There is no 7.25 yet and I have missed nothing. Moving on.
You've missed VTI!!!
(Stirs the pot . . . )
The only difference I see is that WB3 is gross . . . I have zero issues with WB4 (but then again, not on Whinders either . . . ).