Well, people think that KDE is bloated. This is not true. Yes it consumes resources, but the bigger consumer is baloo, which is the file name and context indexer of KDE, which can be turned off with a click. So, In short why I do I use KDE? Let's take a look:
If I need to find something inside a file? There's Baloo, and it's available via KRunner ır Dolphin.
KRunner is also a great comand palette, window changer, and plethora of other tools combined. I generally open Krunner and open applications and do many things over it, no need to touch to mouse.
People rave about dual pane file managers, rightly so. Dolphin is both a single pane and dual pane file manager, rolled in one.
I connect to other services (FTP, SFTP, WebDAV, and whatnot), ah no tools. Dolphin has adapters for all of them. I can directly SFTP into a machine via fish:// for example.
I'm also a big music listener, so I rip some CDs from time to time? Do I need a tool? No. Open Dolphin, navigate to CD. There are folders (MP3, FLAC, OGG, etc.) drag your favorite format to your home folder. It's encoded on the fly. Metadata? It's retrieved when you insert your CD from MusicMatch service and reflected automatically. Neat. No?
More interconnectedness: Add your e-mail accounts and calendars to Akonadi. They are fetched and processed even if your mail client is not running. That's what multitasking is, if you ask me.
People think KDE's eye candy, but it has many quality of life things: Present windows with search, desktop grid with reorganization, dim inactive windows to prevent focus loss and eye fatigue. Just to name a few.
People terminal-hop, but Konsole is one of the best and fastest terminal emulators alongside GNOME's. New guys rave about speed, but this speed optimization thing is done by big boys in 2003-2004. GPU acceleration is also the same story.
KDE is not slow. If you disable windows appearance and destruction animations, things happen before you lift your finger from the button you're pressing. Animations take a bit of time, so things look slow.
KDE guys love GTK as they love Qt. Every KDE release comes with counterpart GTK renderers, so all applications look the same.
So, TWMs, i3/sway, and others are very nice things. They solve a lot of people's problems, and I support these people wholeheartedly, but KDE is an integrated solution which works well across the board. Give it a shot someday, in a VM.
Oh, you want to be pleasantly surprised? Try E17 (Enlightenment 17). That thing is really nice.