If one want to migrate from Windows to Linux, it is good to start with the research if one can find alternatives to all the important Windows software.
There is a list showing alternatives to some popular Windows software.

Alternatives found mostly using https://alternativeto.net/software/

ALPHABETICAL SORTING:

Windows app name - Linux app name - notes
7-zip - 7zip - compressing data
Acronis True Imager WD Edition - gParted, dd - partition handling, system backup
Adobe Reader - Firefox etc..
Advanced Renamer - sed,awk scripts,...
Age of Empires - Wine?/Virtual machine Virtualbox?
AIMP - Clementine - audio player and library
ApexDC - EiskaltDC - file sharing
Avidemux - ...(many) - video editting
Brain Bullet - Wine? - subliminal self suggestion
Debut Video Capture - alternatives exist - screen recording software
DriveImage XML - dd,gparted,? - clone disk/partition and restore
Duplicate Commander - jdupes,...
Duplicate Files Finder - jdupes,...
Everything - locate,? - instant file search by filename
f.lux - f.lux - computer screen dim at evening
FEqual - jdupes,... - find duplicate files
FileZilla - FileZilla - FTP client
firewall/antivirus - iptables,ufw
Flash Mind Booster - wine,... - game
FlylinkDC - EiskaltDC - file sharing
FreeFileSync - rsync - file/folder synchronization
Freemake Video Converter - ...(many) - video cutting and converting
HandBrake - Handbrake,VidCutter,... - video cutting and converting
HD Tune - Wine? - disk surface and performance check
HDD Regenerator - X - not worked on Windows 10
Inkscape - Gimp?
InviDownloader - ffmpeg? - .m4s to .mp4
IrfanView - Viewnior - image viewer and editor
jDownloader - jDownloader - heavy app for downloading files from cloud
Keepass - KeepassXC - password manager
KiTTY - built in terminal
Lingea Lexicon - StarDict - translator
Link Shell Extension - ln
MegaSync - MegaSync/SCP/FTP.. - sync files with cloud storage
MiniTool Partition Wizard - gparted,? - partition recovery, partitioning, backup, cloning
Mozilla Firefox - Firefox
mp3tag - ...(many)
MPC-HC - mplayer,VLC - media player
Natura Sound Therapy - ANoise - relaxation
NeoLoader - Tribler? - file sharing
NoMachine - NoMachine,TightVNC... - VNC client
OpenVPN - OpenVPN - privacy, anonymity
PSPad - pspad,notepad++,... - text editor
PuTTY - built in terminal
qBittorrent - qBittorrent - file sharing
Reasonable NoCLone - jdupes,... - duplicate file dinder
Recuva - TestDisk,R-Studio,... - deleted files recovery
RetroShare - RetroShare - file sharing
SD Card Formtter - dd?
Shareaza - Gtk-Gnutella,quazzaa?,fopnu
Simple Search and Replace - Notepad++,sed,...
SoulseekQt - Nicotine - file sharing
Technitium MAC Address Changer - built-in tools
Test Drive Unlimited - Wine,Virtualbox?,Other PC
TightVNC - VNC Connect
Tor browser - Tor browser
Total Commander - Double Commander,... - file folder manager
Transmission - Transmission - file sharing
Tribler - Tribler - file sharing
Truecrypt - VeraCrypt - encryption
Unetbootin - Unetbootin,balenaEtcher,MultiBootUSB...
VeraCrypt - VeraCrypt - encryption
Virtualbox - Virtualbox - Windows/Linux virtualization
VirtViewer - virt-manager - KVM virtualization VM manager
VirusTotal Uploader - virustotal.com
VLC player - VLC player
VNC Viewer - VNC Connect
Win32DiskImager - dd,... - disc imaging like unetbooting and Rufus
Winamp - Clementine,...
WinDirStat - Baobab,qdirstat - disk usage analysis
WinFF - ffmpeg + gui - video conversion
WinHTTrack Website Copier - HTTrack,wget - archiving websites for offline browsing
WinMerge - WinMerge(Wine)?,Meld,kdiff3,Diffuse - compare/comparison of the files and allow merging differences
WinPcap - tcpdump,libpcap,wireshark - network packets capture
WinSCP - FileZilla,... - FTP, SCP client
WireGuard - WireGuard - VPN security, privacy
Wireshark - Wireshark - network packet analysis
X2Go client - X2Go - virtual desktop
XNViewMP - XNView,Shotwell - image collection viewer

SORTED BY IMPORTANCE: (subjective - 5 high importance, 1 low importance)

Importance - Windows app name - Linux app name - notes
5 - 7-zip - 7zip - compressing data
5 - AIMP - Clementine - audio player and library
5 - ApexDC - EiskaltDC - file sharing
5 - Everything - locate,? - instant file search by filename
5 - FileZilla - FileZilla - FTP client
5 - firewall/antivirus - iptables,ufw
5 - FlylinkDC - EiskaltDC - file sharing
5 - FreeFileSync - rsync - file/folder synchronization
5 - Freemake Video Converter - ...(many) - video cutting and converting
5 - HandBrake - Handbrake,VidCutter,... - video cutting and converting
5 - Keepass - KeepassXC - password manager
5 - KiTTY - built in terminal
5 - Mozilla Firefox - Firefox
5 - MPC-HC - mplayer,VLC - media player
5 - OpenVPN - OpenVPN - privacy, anonymity
5 - PSPad - pspad,notepad++,... - text editor
5 - PuTTY - built in terminal
5 - qBittorrent - qBittorrent - file sharing
5 - Recuva - TestDisk,R-Studio,... - deleted files recovery
5 - Shareaza - Gtk-Gnutella,quazzaa?,fopnu
5 - SoulseekQt - Nicotine - file sharing
5 - Test Drive Unlimited - Wine,Virtualbox?,Other PC
5 - Tor browser - Tor browser
5 - Truecrypt - VeraCrypt - encryption
5 - VeraCrypt - VeraCrypt - encryption
5 - VLC player - VLC player
5 - Winamp - Clementine,...
4 - Advanced Renamer - sed,awk scripts,...
4 - Avidemux - ...(many) - video editting
4 - DriveImage XML - dd,gparted,? - clone disk/partition and restore
4 - Lingea Lexicon - StarDict - translator
4 - MegaSync - MegaSync/SCP/FTP.. - sync files with cloud storage
4 - MiniTool Partition Wizard - gparted,? - partition recovery, partitioning, backup, cloning
4 - TightVNC - VNC Connect
4 - Transmission - Transmission - file sharing
4 - Unetbootin - Unetbootin,balenaEtcher,MultiBootUSB...
4 - VirusTotal Uploader - virustotal.com
4 - VNC Viewer - VNC Connect
4 - WinFF - ffmpeg + gui - video conversion
3 - Acronis True Imager WD Edition - gParted, dd - partition handling, system backup
3 - Adobe Reader - Firefox etc..
3 - Brain Bullet - Wine? - subliminal self suggestion
3 - Debut Video Capture - alternatives exist - screen recording software
3 - Duplicate Commander - jdupes,...
3 - Duplicate Files Finder - jdupes,...
3 - FEqual - jdupes,... - find duplicate files
3 - IrfanView - Viewnior - image viewer and editor
3 - jDownloader - jDownloader - heavy app for downloading files from cloud
3 - Natura Sound Therapy - ANoise - relaxation
3 - Reasonable NoCLone - jdupes,... - duplicate file dinder
3 - RetroShare - RetroShare - file sharing
3 - SD Card Formtter - dd?
3 - Simple Search and Replace - Notepad++,sed,...
3 - Technitium MAC Address Changer - built-in tools
3 - Tribler - Tribler - file sharing
3 - Virtualbox - Virtualbox - Windows/Linux virtualization
3 - Win32DiskImager - dd,... - disc imaging like unetbooting and Rufus
3 - WinHTTrack Website Copier - HTTrack,wget - archiving websites for offline browsing
3 - WinMerge - WinMerge(Wine)?,Meld,kdiff3,Diffuse - compare/comparison of the files and allow merging differences
3 - WinSCP - FileZilla,... - FTP, SCP client
3 - WireGuard - WireGuard - VPN security, privacy
3 - X2Go client - X2Go - virtual desktop
3 - XNViewMP - XNView,Shotwell - image collection viewer
2 - Age of Empires - Wine?/Virtual machine Virtualbox?
2 - f.lux - f.lux - computer screen dim at evening
2 - HD Tune - Wine? - disk surface and performance check
2 - HDD Regenerator - X - not worked on Windows 10
2 - Inkscape - Gimp?
2 - Link Shell Extension - ln
2 - mp3tag - ...(many)
2 - NeoLoader - Tribler? - file sharing
2 - NoMachine - NoMachine,TightVNC... - VNC client
2 - Total Commander - Double Commander,... - file folder manager
2 - WinDirStat - Baobab,qdirstat - disk usage analysis
2 - Wireshark - Wireshark - network packet analysis
1 - Flash Mind Booster - wine,... - game
1 - InviDownloader - ffmpeg? - .m4s to .mp4
1 - VirtViewer - virt-manager - KVM virtualization VM manager
1 - WinPcap - tcpdump,libpcap,wireshark - network packets capture