Should I suggest him manjaro or linux mint cinnamon 
What about KDE?
Yaa sure
Any suggestions??
He can install KDE Neon, or even Fedora 34 and Fedora Spins.
There is also MXLinux and Antix.
Really, your friend can try Zorin OS Lite and then do what many of us (Self included have done): Distro hop and enjoy the journey.
@Dixit Bro community support is also a major factor while choosing a distro. I suggest him to try Zorin OS Lite and I believe it will work great for him as I am also using the Zorin Core on 4GB i3 6th gen lappy.
Ok I will re download Zorin OS iso and check again.
Also I don't even feel like leaving Zorin
Ok then what I understandable Zorin Lite is full integrated with xfce DE but Zorin Lite Pro have some Gnome mixed with xfce desktop. I am wright?
Both utilize Gnome applications, but Zorin OS Lite Pro may include more of them.
Then in many distributions exist full clear xfce?
i will surely recommend zorin os 15 education since i had used it on core i3 2330M processor x64 variant with 2gb ram so i am pretty sure it didnt lag so neither zorin os 16 will on your pc.
Ok we talking here about best distribution. Then best and fast help distribution is processor,ssd and ram?
Linux Mint Cinnamon or XFCE for even better performance...
ok for amazing visuals and tweaks different from the main stream i would recommend garuda linux kde dragonized variant but only to pro not newbies since based on arch and needs high specs.
You mean gentoo also is arch and could be a xfce? Professionals people.
Solus MATE is pretty good.
The live edition of Devuan 3.0 used xfce but I notice on more recent edition a move to LXQt - try the live edition of Devuan 4. There is 64-bit and 32-bit isos from the first mirror I clicked on here:
Zorin Lite is as good a distro for those specs as any - and better than most. Linux Mint XFCE is also very good (even Mint Cinnamon would run well.) Peppermint is another distro that uses XFCE and is really quick.